The following sections include common types of native crash, an analysis of a
sample crash dump, and a discussion of tombstones. Each crash type includes
example debuggerd output with key evidence highlighted to help
you distinguish the specific kind of crash.
Abort
Aborts are interesting because they are deliberate. There are many different
ways to abort (including calling
abort(3),
failing an
assert(3),
using one of the Android-specific fatal logging types), but all involve
calling abort. A call to abort signals the calling
thread with SIGABRT, so a frame showing "abort" in libc.so plus
SIGABRT are the things to look for in the debuggerd output to
recognize this case.
There may be an explicit "abort message" line. You should also look in the
logcat output to see what this thread logged before deliberately
killing itself, because unlike assert(3) or high level fatal
logging facilities, abort(3) doesn't accept a message.
Current versions of Android inline the
tgkill(2)
system call, so their stacks are the easiest to read, with the call to
abort(3) at the very top:
pid: 4637, tid: 4637, name: crasher >>> crasher <<SIGABRT), code -6 (SI_TKILL), fault addr -------- Abort message: 'some_file.c:123: some_function: assertion "false" failed' r0 00000000 r1 0000121d r2 00000006 r3 00000008 r4 0000121d r5 0000121d r6 ffb44a1c r7 0000010c r8 00000000 r9 00000000 r10 00000000 r11 00000000 ip ffb44c20 sp ffb44a08 lr eace2b0b pc eace2b16 backtrace: #00 pc 0001cb16 /system/lib/libc.so (abort+57) #01 pc 0001cd8f /system/lib/libc.so (__assert2+22) #02 pc 00001531 /system/bin/crasher (do_action+764) #03 pc 00002301 /system/bin/crasher (main+68) #04 pc 0008a809 /system/lib/libc.so (__libc_init+48) #05 pc 00001097 /system/bin/crasher (_start_main+38)
Older versions of Android followed a convoluted path between the original
abort call (frame 4 here) and the actual sending of the signal (frame 0 here).
This was especially true on 32-bit ARM, which added
__libc_android_abort (frame 3 here) to the other platforms'
sequence of raise/pthread_kill/tgkill:
pid: 1656, tid: 1656, name: crasher >>> crasher <<SIGABRT), code -6 (SI_TKILL), fault addr -------- Abort message: 'some_file.c:123: some_function: assertion "false" failed' r0 00000000 r1 00000678 r2 00000006 r3 f70b6dc8 r4 f70b6dd0 r5 f70b6d80 r6 00000002 r7 0000010c r8 ffffffed r9 00000000 sl 00000000 fp ff96ae1c ip 00000006 sp ff96ad18 lr f700ced5 pc f700dc98 cpsr 400b0010 backtrace: #00 pc 00042c98 /system/lib/libc.so (tgkill+12) #01 pc 00041ed1 /system/lib/libc.so (pthread_kill+32) #02 pc 0001bb87 /system/lib/libc.so (raise+10) #03 pc 00018cad /system/lib/libc.so (__libc_android_abort+34) #04 pc 000168e8 /system/lib/libc.so (abort+4) #05 pc 0001a78f /system/lib/libc.so (__libc_fatal+16) #06 pc 00018d35 /system/lib/libc.so (__assert2+20) #07 pc 00000f21 /system/xbin/crasher #08 pc 00016795 /system/lib/libc.so (__libc_init+44) #09 pc 00000abc /system/xbin/crasher
You can reproduce an instance of this type of crash using crasher
abort.
Pure null pointer dereference
This is the classic native crash, and although it's just a special case of the next crash type, it's worth mentioning separately because it usually requires the least thought.
In the example below, even though the crashing function is in
libc.so, because the string functions just operate on the
pointers they're given, you can infer that
strlen(3)
was called with a null pointer; and this crash should go straight to the
author of the calling code. In this case, frame #01 is the bad caller.
pid: 25326, tid: 25326, name: crasher >>> crasher <<SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x0 r0 00000000 r1 00000000 r2 00004c00 r3 00000000 r4 ab088071 r5 fff92b34 r6 00000002 r7 fff92b40 r8 00000000 r9 00000000 sl 00000000 fp fff92b2c ip ab08cfc4 sp fff92a08 lr ab087a93 pc efb78988 cpsr 600d0030 backtrace: #00 pc 00019988 /system/lib/libc.so (strlen+71) #01 pc 00001a8f /system/xbin/crasher (strlen_null+22) #02 pc 000017cd /system/xbin/crasher (do_action+948) #03 pc 000020d5 /system/xbin/crasher (main+100) #04 pc 000177a1 /system/lib/libc.so (__libc_init+48) #05 pc 000010e4 /system/xbin/crasher (_start+96)
You can reproduce an instance of this type of crash using crasher
strlen-NULL.
Low-address null pointer dereference
In many cases the fault address won't be 0, but some other low number. Two- or
three-digit addresses in particular are very common, whereas a six-digit
address is almost certainly not a null pointer dereference—that would
require a 1MiB offset. This usually occurs when you have code that
dereferences a null pointer as if it was a valid struct. Common functions are
fprintf(3)
(or any other function taking a FILE*) and
readdir(3),
because code often fails to check that the
fopen(3)
or
opendir(3)
call actually succeeded first.
Here's an example of readdir:
pid: 25405, tid: 25405, name: crasher >>> crasher <<SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0xc r0 0000000c r1 00000000 r2 00000000 r3 3d5f0000 r4 00000000 r5 0000000c r6 00000002 r7 ff8618f0 r8 00000000 r9 00000000 sl 00000000 fp ff8618dc ip edaa6834 sp ff8617a8 lr eda34a1f pc eda618f6 cpsr 600d0030 backtrace: #00 pc 000478f6 /system/lib/libc.so (pthread_mutex_lock+1) #01 pc 0001aa1b /system/lib/libc.so (readdir+10) #02 pc 00001b35 /system/xbin/crasher (readdir_null+20) #03 pc 00001815 /system/xbin/crasher (do_action+976) #04 pc 000021e5 /system/xbin/crasher (main+100) #05 pc 000177a1 /system/lib/libc.so (__libc_init+48) #06 pc 00001110 /system/xbin/crasher (_start+96)
Here the direct cause of the crash is that
pthread_mutex_lock(3)
has tried to access address 0xc (frame 0). But the first thing
pthread_mutex_lock does is dereference the state
element of the pthread_mutex_t* it was given. If you look at the
source, you can see that element is at offset 0 in the struct, which tells you
that pthread_mutex_lock was given the invalid pointer 0xc. From
frame 1 you can see that it was given that pointer by readdir,
which extracts the mutex_ field from the DIR* it's
given. Looking at that structure, you can see that mutex_ is at
offset sizeof(int) + sizeof(size_t) + sizeof(dirent*) into
struct DIR, which on a 32-bit device is 4 + 4 + 4 = 12 = 0xc, so
you found the bug: readdir was passed a null pointer by the
caller. At this point you can paste the stack into the stack tool to find out
where in logcat this happened.
struct DIR {
int fd_;
size_t available_bytes_;
dirent* next_;
pthread_mutex_t mutex_;
dirent buff_[15];
long current_pos_;
};
In most cases you can actually skip this analysis. A sufficiently low fault
address usually means you can just skip any libc.so frames in the
stack and directly accuse the calling code. But not always, and this is how
you would present a compelling case.
You can reproduce instances of this kind of crash using crasher
fprintf-NULL or crasher readdir-NULL.
FORTIFY failure
A FORTIFY failure is a special case of an abort that occurs when the C library
detects a problem that might lead to a security vulnerability. Many C library
functions are fortified; they take an extra argument that tells them
how large a buffer actually is and check at run time whether the operation
you're trying to perform actually fits. Here's an example where the code tries
to read(fd, buf, 32) into a buffer that's actually only 10 bytes
long...
pid: 25579, tid: 25579, name: crasher >>> crasher <<FORTIFY: read: prevented 32-byte write into 10-byte buffer' r0 00000000 r1 000063eb r2 00000006 r3 00000008 r4 ff96f350 r5 000063eb r6 000063eb r7 0000010c r8 00000000 r9 00000000 sl 00000000 fp ff96f49c ip 00000000 sp ff96f340 lr ee83ece3 pc ee86ef0c cpsr 000d0010 backtrace: #00 pc 00049f0c /system/lib/libc.so (tgkill+12) #01 pc 00019cdf /system/lib/libc.so (abort+50) #02 pc 0001e197 /system/lib/libc.so (__fortify_fatal+30) #03 pc 0001baf9 /system/lib/libc.so (__read_chk+48) #04 pc 0000165b /system/xbin/crasher (do_action+534) #05 pc 000021e5 /system/xbin/crasher (main+100) #06 pc 000177a1 /system/lib/libc.so (__libc_init+48) #07 pc 00001110 /system/xbin/crasher (_start+96)
You can reproduce an instance of this type of crash using crasher
fortify.
Stack corruption detected by -fstack-protector
The compiler's -fstack-protector option inserts checks into
functions with on-stack buffers to guard against buffer overruns. This option
is on by default for platform code but not for apps. When this option is
enabled, the compiler adds instructions to the
function
prologue to write a random value just past the last local on the stack and
to the function epilogue to read it back and check that it's not changed. If
that value changed, it was overwritten by a buffer overrun, so the epilogue
calls __stack_chk_fail to log a message and abort.
pid: 26717, tid: 26717, name: crasher >>> crasher <<Abort message: 'stack corruption detected' r0 00000000 r1 0000685d r2 00000006 r3 00000008 r4 ffd516d8 r5 0000685d r6 0000685d r7 0000010c r8 00000000 r9 00000000 sl 00000000 fp ffd518bc ip 00000000 sp ffd516c8 lr ee63ece3 pc ee66ef0c cpsr 000e0010 backtrace: #00 pc 00049f0c /system/lib/libc.so (tgkill+12) #01 pc 00019cdf /system/lib/libc.so (abort+50) #02 pc 0001e07d /system/lib/libc.so (__libc_fatal+24) #03 pc 0004863f /system/lib/libc.so (__stack_chk_fail+6) #04 pc 000013ed /system/xbin/crasher (smash_stack+76) #05 pc 00001591 /system/xbin/crasher (do_action+280) #06 pc 00002219 /system/xbin/crasher (main+100) #07 pc 000177a1 /system/lib/libc.so (__libc_init+48) #08 pc 00001144 /system/xbin/crasher (_start+96)
You can distinguish this from other kinds of abort by the presence of
__stack_chk_fail in the backtrace and the specific abort message.
You can reproduce an instance of this type of crash using crasher
smash-stack.
Seccomp SIGSYS from a disallowed system call
The seccomp
system (specifically seccomp-bpf) restricts access to system calls. For more
information about seccomp for platform developers, see the blog post
Seccomp
filter in Android O. A thread that calls a restricted system call will
receive a SIGSYS signal with code SYS_SECCOMP. The system call number will be
shown in the cause line, along with the architecture. It is important to note
that system call numbers vary between architectures. For example, the
readlinkat(2) system call is number 305 on x86 but 267 on x86-64.
The call number is different again on both arm and arm64. Because system call
numbers vary between architectures, it's usually easier to use the stack trace
to find out which system call was disallowed rather than looking for the
system call number in the headers.
pid: 11046, tid: 11046, name: crasher >>> crasher <<SYS_SECCOMP), fault addr -------- Cause: seccomp prevented call to disallowed arm system call 99999 r0 cfda0444 r1 00000014 r2 40000000 r3 00000000 r4 00000000 r5 00000000 r6 00000000 r7 0001869f r8 00000000 r9 00000000 sl 00000000 fp fffefa58 ip fffef898 sp fffef888 lr 00401997 pc f74f3658 cpsr 600f0010 backtrace: #00 pc 00019658 /system/lib/libc.so (syscall+32) #01 pc 00001993 /system/bin/crasher (do_action+1474) #02 pc 00002699 /system/bin/crasher (main+68) #03 pc 0007c60d /system/lib/libc.so (__libc_init+48) #04 pc 000011b0 /system/bin/crasher (_start_main+72)
You can distinguish disallowed system calls from other crashes by the presence of
SYS_SECCOMP on the signal line and the description on the cause line.
You can reproduce an instance of this type of crash using crasher
seccomp.
Execute-only memory violation (Android 10 only)
For arm64 in Android 10 only, executable segments of binaries and libraries were mapped into memory execute-only (non-readable) as a hardening technique against code-reuse attacks. This mitigation interacted badly with other mitigations and was later removed.
Making code unreadable causes intentional and unintentional reads into memory segments marked
execute-only to throw a SIGSEGV with code SEGV_ACCERR. This might
occur as a result of a bug, vulnerability, data mixed with code (such as a literal pool),
or intentional memory introspection.
The compiler assumes code and data are not intermixed, but issues can arise from hand-written
assembly. In many cases these can be fixed by simply moving the constants to a .data
section.
If code introspection is absolutely necessary on executable code sections,
mprotect(2)
should be called first to mark the code readable, and then again to mark it unreadable after the
operation is completed.
pid: 2938, tid: 2940, name: crasher64 >>> crasher64 <<Cause: execute-only (no-read) memory access error; likely due to data in .text. x0 0000000000000000 x1 0000005f2cecf21f x2 0000000000000078 x3 0000000000000053 x4 0000000000000074 x5 8000000000000000 x6 ff71646772607162 x7 00000020dcf0d16c x8 0000005f2ced24a8 x9 000000781251c55e x10 0000000000000000 x11 0000000000000000 x12 0000000000000014 x13 ffffffffffffffff x14 0000000000000002 x15 ffffffffffffffff x16 0000005f2ced52f0 x17 00000078125c0ed8 x18 0000007810e8e000 x19 00000078119fbd50 x20 00000078125d6020 x21 00000078119fbd50 x22 00000b7a00000b7a x23 00000078119fbdd8 x24 00000078119fbd50 x25 00000078119fbd50 x26 00000078119fc018 x27 00000078128ea020 x28 00000078119fc020 x29 00000078119fbcb0 sp 00000078119fba40 lr 0000005f2ced1b94 pc 0000005f2ced1ba4 backtrace: #00 pc 0000000000003ba4 /system/bin/crasher64 (do_action+2348) #01 pc 0000000000003234 /system/bin/crasher64 (thread_callback+44) #02 pc 00000000000e2044 /apex/com.android.runtime/lib64/bionic/libc.so (__pthread_start(void*)+36) #03 pc 0000000000083de0 /apex/com.android.runtime/lib64/bionic/libc.so (__start_thread+64)
You can distinguish execute-only memory violations from other crashes by the cause line.
You can reproduce an instance of this type of crash using crasher xom.
Error detected by fdsan
Android's fdsan file descriptor sanitizer helps catch common mistakes with file descriptors such as use-after-close and double-close. See the fdsan documentation for more details about debugging (and avoiding) this class of errors.
pid: 32315, tid: 32315, name: crasher64 >>> crasher64 <<< signal 35 (), code -1 (SI_QUEUE), fault addr -------- Abort message: 'attempted to close file descriptor 3, expected to be unowned, actually owned by FILE* 0x7d8e413018' x0 0000000000000000 x1 0000000000007e3b x2 0000000000000023 x3 0000007fe7300bb0 x4 3033313465386437 x5 3033313465386437 x6 3033313465386437 x7 3831303331346538 x8 00000000000000f0 x9 0000000000000000 x10 0000000000000059 x11 0000000000000034 x12 0000007d8ebc3a49 x13 0000007fe730077a x14 0000007fe730077a x15 0000000000000000 x16 0000007d8ec9a7b8 x17 0000007d8ec779f0 x18 0000007d8f29c000 x19 0000000000007e3b x20 0000000000007e3b x21 0000007d8f023020 x22 0000007d8f3b58dc x23 0000000000000001 x24 0000007fe73009a0 x25 0000007fe73008e0 x26 0000007fe7300ca0 x27 0000000000000000 x28 0000000000000000 x29 0000007fe7300c90 sp 0000007fe7300860 lr 0000007d8ec2f22c pc 0000007d8ec2f250 backtrace: #00 pc 0000000000088250 /bionic/lib64/libc.so (fdsan_error(char const*, ...)+384) #01 pc 0000000000088060 /bionic/lib64/libc.so (android_fdsan_close_with_tag+632) #02 pc 00000000000887e8 /bionic/lib64/libc.so (close+16) #03 pc 000000000000379c /system/bin/crasher64 (do_action+1316) #04 pc 00000000000049c8 /system/bin/crasher64 (main+96) #05 pc 000000000008021c /bionic/lib64/libc.so (_start_main)
You can distinguish this from other kinds of abort by the presence of
fdsan_error in the backtrace and the specific abort message.
You can reproduce an instance of this type of crash using
crasher fdsan_file or crasher fdsan_dir.
Investigate crash dumps
If you don't have a specific crash that you're investigating right now, the
platform source includes a tool for testing debuggerd called
crasher. If you mm in system/core/debuggerd/ you'll
get both a crasher and a crasher64 on your path (the
latter allowing you to test 64-bit crashes). Crasher can crash in a large
number of interesting ways based on the command line arguments you provide.
Use crasher --help to see the currently supported selection.
To introduce the different pieces in a crash dump, let's work through this example crash dump:
*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
Build fingerprint: 'Android/aosp_flounder/flounder:5.1.51/AOSP/enh08201009:eng/test-keys'
Revision: '0'
ABI: 'arm'
pid: 1656, tid: 1656, name: crasher >>> crasher <<<
signal 6 (SIGABRT), code -6 (SI_TKILL), fault addr --------
Abort message: 'some_file.c:123: some_function: assertion "false" failed'
r0 00000000 r1 00000678 r2 00000006 r3 f70b6dc8
r4 f70b6dd0 r5 f70b6d80 r6 00000002 r7 0000010c
r8 ffffffed r9 00000000 sl 00000000 fp ff96ae1c
ip 00000006 sp ff96ad18 lr f700ced5 pc f700dc98 cpsr 400b0010
backtrace:
#00 pc 00042c98 /system/lib/libc.so (tgkill+12)
#01 pc 00041ed1 /system/lib/libc.so (pthread_kill+32)
#02 pc 0001bb87 /system/lib/libc.so (raise+10)
#03 pc 00018cad /system/lib/libc.so (__libc_android_abort+34)
#04 pc 000168e8 /system/lib/libc.so (abort+4)
#05 pc 0001a78f /system/lib/libc.so (__libc_fatal+16)
#06 pc 00018d35 /system/lib/libc.so (__assert2+20)
#07 pc 00000f21 /system/xbin/crasher
#08 pc 00016795 /system/lib/libc.so (__libc_init+44)
#09 pc 00000abc /system/xbin/crasher
Tombstone written to: /data/tombstones/tombstone_06
*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***
The line of asterisks with spaces is helpful if you're searching a log for native crashes. The string "*** ***" rarely shows up in logs other than at the beginning of a native crash.
Build fingerprint: 'Android/aosp_flounder/flounder:5.1.51/AOSP/enh08201009:eng/test-keys'
The fingerprint lets you identify exactly which build the crash occurred on.
This is exactly the same as the ro.build.fingerprint system
property.
Revision: '0'
The revision refers to the hardware rather than the software. This is usually
unused but can be useful to help you automatically ignore bugs known to be
caused by bad hardware. This is exactly the same as the
ro.revision system property.
ABI: 'arm'
The ABI is one of arm, arm64, x86, or x86-64. This is mostly
useful for the stack script mentioned above, so that it knows
what toolchain to use.
pid: 1656, tid: 1656, name: crasher >>> crasher <<<
This line identifies the specific thread in the process that crashed. In this case, it was the process' main thread, so the process ID and thread ID match. The first name is the thread name, and the name surrounded by >>> and <<< is the process name. For an app, the process name is typically the fully-qualified package name (such as com.facebook.katana), which is useful when filing bugs or trying to find the app in Google Play. The pid and tid can also be useful in finding the relevant log lines preceding the crash.
signal 6 (SIGABRT), code -6 (SI_TKILL), fault addr --------
This line tells you which signal (SIGABRT) was received, and more about how it
was received (SI_TKILL). The signals reported by debuggerd are
SIGABRT, SIGBUS, SIGFPE, SIGILL, SIGSEGV, and SIGTRAP. The signal-specific
codes vary based on the specific signal.
Abort message: 'some_file.c:123: some_function: assertion "false" failed'
Not all crashes will have an abort message line, but aborts will. This is automatically gathered from the last line of fatal logcat output for this pid/tid, and in the case of a deliberate abort is likely to give an explanation of why the program killed itself.
r0 00000000 r1 00000678 r2 00000006 r3 f70b6dc8 r4 f70b6dd0 r5 f70b6d80 r6 00000002 r7 0000010c r8 ffffffed r9 00000000 sl 00000000 fp ff96ae1c ip 00000006 sp ff96ad18 lr f700ced5 pc f700dc98 cpsr 400b0010
The register dump shows the content of the CPU registers at the time the signal was received. (This section varies wildly between ABIs.) How useful these are will depend on the exact crash.
backtrace:
#00 pc 00042c98 /system/lib/libc.so (tgkill+12)
#01 pc 00041ed1 /system/lib/libc.so (pthread_kill+32)
#02 pc 0001bb87 /system/lib/libc.so (raise+10)
#03 pc 00018cad /system/lib/libc.so (__libc_android_abort+34)
#04 pc 000168e8 /system/lib/libc.so (abort+4)
#05 pc 0001a78f /system/lib/libc.so (__libc_fatal+16)
#06 pc 00018d35 /system/lib/libc.so (__assert2+20)
#07 pc 00000f21 /system/xbin/crasher
#08 pc 00016795 /system/lib/libc.so (__libc_init+44)
#09 pc 00000abc /system/xbin/crasher
The backtrace shows you where in the code we were at the time of crash. The
first column is the frame number (matching gdb's style where the deepest frame
is 0). The PC values are relative to the location of the shared library rather
than absolute addresses. The next column is the name of the mapped region
(which is usually a shared library or executable, but might not be for, say,
JIT-compiled code). Finally, if symbols are available, the symbol that the PC
value corresponds to is shown, along with the offset into that symbol in
bytes. You can use this in conjunction with objdump(1) to find
the corresponding assembler instruction.
Read tombstones
Tombstone written to: /data/tombstones/tombstone_06
This tells you where debuggerd wrote extra information.
debuggerd will keep up to 10 tombstones, cycling through the
numbers 00 to 09 and overwriting existing tombstones as necessary.
The tombstone contains the same information as the crash dump, plus a few
extras. For example, it includes backtraces for all threads (not
just the crashing thread), the floating point registers, raw stack dumps,
and memory dumps around the addresses in registers. Most usefully it also
includes a full memory map (similar to /proc/pid/maps).
Here's an annotated example from a 32-bit ARM process crash:
memory map: (fault address prefixed with --->) --->ab15f000-ab162fff r-x 0 4000 /system/xbin/crasher (BuildId: b9527db01b5cf8f5402f899f64b9b121)
There are two things to note here. The first is that this line is prefixed with "--->". The maps are most useful when your crash isn't just a null pointer dereference. If the fault address is small, it's probably some variant of a null pointer dereference. Otherwise looking at the maps around the fault address can often give you a clue as to what happened. Some possible issues that can be recognized by looking at the maps include:
- Reads/writes past the end of a block of memory.
- Reads/writes before the beginning of a block of memory.
- Attempts to execute non-code.
- Running off the end of a stack.
- Attempts to write to code (as in the example above).
The second thing to note is that executables and shared libraries files will
show the BuildId (if present) in Android 6.0 and higher, so you can see exactly
which version of your code crashed. Platform binaries include a BuildId by
default since Android 6.0; NDK r12 and higher automatically pass
-Wl,--build-id to the linker too.
ab163000-ab163fff r-- 3000 1000 /system/xbin/crasher ab164000-ab164fff rw- 0 1000 f6c80000-f6d7ffff rw- 0 100000 [anon:libc_malloc]
On Android the heap isn't necessarily a single region. Heap regions will
be labeled [anon:libc_malloc].
f6d82000-f6da1fff r-- 0 20000 /dev/__properties__/u:object_r:logd_prop:s0 f6da2000-f6dc1fff r-- 0 20000 /dev/__properties__/u:object_r:default_prop:s0 f6dc2000-f6de1fff r-- 0 20000 /dev/__properties__/u:object_r:logd_prop:s0 f6de2000-f6de5fff r-x 0 4000 /system/lib/libnetd_client.so (BuildId: 08020aa06ed48cf9f6971861abf06c9d) f6de6000-f6de6fff r-- 3000 1000 /system/lib/libnetd_client.so f6de7000-f6de7fff rw- 4000 1000 /system/lib/libnetd_client.so f6dec000-f6e74fff r-x 0 89000 /system/lib/libc++.so (BuildId: 8f1f2be4b37d7067d366543fafececa2) (load base 0x2000) f6e75000-f6e75fff --- 0 1000 f6e76000-f6e79fff r-- 89000 4000 /system/lib/libc++.so f6e7a000-f6e7afff rw- 8d000 1000 /system/lib/libc++.so f6e7b000-f6e7bfff rw- 0 1000 [anon:.bss] f6e7c000-f6efdfff r-x 0 82000 /system/lib/libc.so (BuildId: d189b369d1aafe11feb7014d411bb9c3) f6efe000-f6f01fff r-- 81000 4000 /system/lib/libc.so f6f02000-f6f03fff rw- 85000 2000 /system/lib/libc.so f6f04000-f6f04fff rw- 0 1000 [anon:.bss] f6f05000-f6f05fff r-- 0 1000 [anon:.bss] f6f06000-f6f0bfff rw- 0 6000 [anon:.bss] f6f0c000-f6f21fff r-x 0 16000 /system/lib/libcutils.so (BuildId: d6d68a419dadd645ca852cd339f89741) f6f22000-f6f22fff r-- 15000 1000 /system/lib/libcutils.so f6f23000-f6f23fff rw- 16000 1000 /system/lib/libcutils.so f6f24000-f6f31fff r-x 0 e000 /system/lib/liblog.so (BuildId: e4d30918d1b1028a1ba23d2ab72536fc) f6f32000-f6f32fff r-- d000 1000 /system/lib/liblog.so f6f33000-f6f33fff rw- e000 1000 /system/lib/liblog.so
Typically, a shared library has three adjacent entries. One is readable and
executable (code), one is read-only (read-only data), and one is read-write
(mutable data). The first column shows the address ranges for the mapping, the
second column the permissions (in the usual Unix ls(1) style),
the third column the offset into the file (in hex), the fourth column the size
of the region (in hex), and the fifth column the file (or other region name).
f6f34000-f6f53fff r-x 0 20000 /system/lib/libm.so (BuildId: 76ba45dcd9247e60227200976a02c69b) f6f54000-f6f54fff --- 0 1000 f6f55000-f6f55fff r-- 20000 1000 /system/lib/libm.so f6f56000-f6f56fff rw- 21000 1000 /system/lib/libm.so f6f58000-f6f58fff rw- 0 1000 f6f59000-f6f78fff r-- 0 20000 /dev/__properties__/u:object_r:default_prop:s0 f6f79000-f6f98fff r-- 0 20000 /dev/__properties__/properties_serial f6f99000-f6f99fff rw- 0 1000 [anon:linker_alloc_vector] f6f9a000-f6f9afff r-- 0 1000 [anon:atexit handlers] f6f9b000-f6fbafff r-- 0 20000 /dev/__properties__/properties_serial f6fbb000-f6fbbfff rw- 0 1000 [anon:linker_alloc_vector] f6fbc000-f6fbcfff rw- 0 1000 [anon:linker_alloc_small_objects] f6fbd000-f6fbdfff rw- 0 1000 [anon:linker_alloc_vector] f6fbe000-f6fbffff rw- 0 2000 [anon:linker_alloc] f6fc0000-f6fc0fff r-- 0 1000 [anon:linker_alloc] f6fc1000-f6fc1fff rw- 0 1000 [anon:linker_alloc_lob] f6fc2000-f6fc2fff r-- 0 1000 [anon:linker_alloc] f6fc3000-f6fc3fff rw- 0 1000 [anon:linker_alloc_vector] f6fc4000-f6fc4fff rw- 0 1000 [anon:linker_alloc_small_objects] f6fc5000-f6fc5fff rw- 0 1000 [anon:linker_alloc_vector] f6fc6000-f6fc6fff rw- 0 1000 [anon:linker_alloc_small_objects] f6fc7000-f6fc7fff rw- 0 1000 [anon:arc4random _rsx structure] f6fc8000-f6fc8fff rw- 0 1000 [anon:arc4random _rs structure] f6fc9000-f6fc9fff r-- 0 1000 [anon:atexit handlers] f6fca000-f6fcafff --- 0 1000 [anon:thread signal stack guard page]
As of Android 5.0, the C library names most of its anonymous mapped regions so there are fewer mystery regions.
f6fcb000-f6fccfff rw- 0 2000 [stack:5081]
Regions named [stack:tid] are the stacks for the given
threads.
f6fcd000-f702afff r-x 0 5e000 /system/bin/linker (BuildId: 84f1316198deee0591c8ac7f158f28b7) f702b000-f702cfff r-- 5d000 2000 /system/bin/linker f702d000-f702dfff rw- 5f000 1000 /system/bin/linker f702e000-f702ffff rw- 0 2000 f7030000-f7030fff r-- 0 1000 f7031000-f7032fff rw- 0 2000 ffcd7000-ffcf7fff rw- 0 21000 ffff0000-ffff0fff r-x 0 1000 [vectors]
Whether you see [vector] or [vdso] depends on the
architecture. ARM uses [vector], while all other architectures use
[vdso].