The discussion on LKML is converging on v16 of the fault address tag
bits patch [1]. In this version of the patch the presence of the tag
bits in si_addr is controlled by a sa_flags bit, and a protocol is
introduced to allow userspace to detect kernel support for sa_flags
bits. Update the tombstone signal handler to use this API to read
the tag bits, update the interceptors in libsigchain to implement
the flag support detection protocol and hide the tag bits in si_addr
from chained signal handlers that did not request them to match the
kernel behavior.
[1] https://lore.kernel.org/linux-arm-kernel/cover.1605235762.git.pcc@google.com/
Change-Id: I57f24c07c01ceb3e5b81cfc15edf559ef7dfc740
This simplifies some of the logic and removes the need to pass an
Arch value to functions that should already know about the arch
it is operating on.
Includes fixes for debuggerd/libbacktrace.
Added new unit tests to cover new cases.
Test: All unit tests pass.
Test: Faked unwinder failing to verify debuggerd error messages display
Test: properly in backtrace and tombstone.
Change-Id: I439fcae0695befcfb1cb4c0a786cc74949d33425
This value indicates whether memory tagging is enabled on a thread,
the mode (sync or async) and the set of excluded tags. This information
can sometimes be important for understanding an MTE related crash,
so include it in the per-thread tombstone output.
Bug: 135772972
Change-Id: I25a16e10ac7fbb2b1ab2a961a5279f787039000b
Teach debuggerd to use the new scudo APIs proposed in
https://reviews.llvm.org/D77283 for extracing MTE error reports from crashed
processes, and include those reports in tombstones if possible.
Bug: 135772972
Change-Id: I082dfd0ac9d781cfed2b8c34cc73562614bb0dbb
On aarch64, the top 8 bits of the address (i.e. the tag bits) of
the fault address in si_addr are always clear. This isn't ideal for
MTE which will require these bits in order to correctly diagnose
tag mismatches.
A proposed kernel patch [1] exposes the full fault address including
the tag bits as part of the ucontext. Change debuggerd to read this
fault address if available.
[1] https://patchwork.kernel.org/patch/11435077/
Bug: 135772972
Change-Id: Ia05be574113860f4e9ecc36a310c4b740e0c4afb
Similar to r.android.com/1247247 I'll be adding more of them for MTE.
Also, change the protocol between the crasher and crash_dump to make
it easier to add new fields and change the referenced data structures
without needing to worry about versioning. The version number for
static executables is now always 1 (where the protocol will never
change), while the version number for dynamic executables is always
4 (where the protocol can change, because the linker and crash_dump
are version locked).
Bug: 135772972
Change-Id: Ib4696d0544d7c87cb429aaaa15f18c3640059e16
We're now passing around a couple of addresses for GWP-ASan in addition
to abort_msg_address and fdsan_table_address, and I'm going to need to add
more of them for MTE. Move them into a data structure in order to simplify
various function signatures.
Bug: 135772972
Change-Id: Ie01e1bd93a9ab64f21865f56574696825a6a125f
GWP-ASan can provide information about a crash that it caused. Grab the
GWP-ASan regions from the globals shared by the linker for crash-handler
purpopses, pull the information from GWP-ASan, and display it.
This adds two regions:
1. Causality tracking by GWP-ASan. We now print a cause header about
the crash, like `Cause: [GWP-ASan]: Use After Free on a 1-byte
allocation at 0x7365bb3ff8`
2. Allocation and deallocation stack traces.
Bug: 135634846
Test: atest debuggerd_test
Change-Id: Id28d5400c9a9a053fcde83a4788f971e677d4643
There appears to be a kernel bug that causes SIGHUP and SIGCONT to be
sent to the parent process group we spawn from if the process group
contains stopped jobs (e.g. the parent itself, because of wait_for_gdb).
Call setsid in all of our children to prevent this from happening.
Bug: http://b/31124563
Test: adb shell 'setprop debug.debuggerd.wait_for_gdb 1; killall -ABRT surfaceflinger'
Change-Id: I1a48d70886880a5bfbe2deb80d48deece55faf09
Update the entries only when the list is modified by the runtime.
Check that the list wasn't concurrently modified when being read.
Bug: 124287208
Test: libunwindstack_test
Test: art/test.py -b --host -r -t 137-cfi
Change-Id: I87ba70322053a01b3d5be1fdf6310e1dc21bb084
Small modifications to the dump_stack method and added unit tests to
verify the output.
Bug: 120606663
Test: Unit tests pass, debuggerd run on processes on target.
Change-Id: Id385a915b751abda3dd6baebed6c3ce498c3bf6e
There is a problem about tombstone, which it will fail to
generate tombstone file in some scenarios due to socket
communication exception.
Reproduce step:
step 1: reboot device
step 2: ps -ef |grep zygote , get the pid of zygote64
(Attention: zygote64 should never been killed or reboot,
otherwise we can get the tombstone file)
step 3: kill -5 pid of zygote64
step 4: cd data/tombstones/, and could not find the tombstone
file of zygote64.
[Cause Analysis]
1. There are following logs by logcat:
11-19 15:38:43.789 569 569 F libc : Fatal signal 5 (SIGTRAP),
code 0 (SI_USER) in tid 569 (main), pid 569 (main)
11-19 15:38:43.829 6115 6115 I crash_dump64: obtaining output
fd from tombstoned, type: kDebuggerdTombstone
11-19 15:38:43.830 569 5836 I Zygote : Process 6114 exited
cleanly (0)
11-19 15:38:43.830 777 777 I /system/bin/tombstoned: received
crash request for pid 569
11-19 15:38:43.831 6115 6115 I crash_dump64: performing dump of
process 569 (target tid = 569)
...
11-19 15:38:43.937 777 777 W /system/bin/tombstoned: crash
socket received short read of length 0 (expected 12)
2. The last log was print by function of crash_request_cb in
file of tombstoned.cpp, following related code:
rc = TEMP_FAILURE_RETRY(read(sockfd, &request, sizeof(request)));
if (rc == -1) {
PLOG(WARNING) << "failed to read from crash socket";
goto fail;
} else if (rc != sizeof(request)) {
LOG(WARNING) << "crash socket received short read of length " << rc << " (expected "
<< sizeof(request) << ")";
goto fail;
}
Tombstoned read message by socket, and now the message length is
zero. Some socket communication exception occurs at that time.
We try to let crash_dump resend the socket message when the
communication is abnormal. Just as this CL.
Test: 1 reboot device
2 ps -ef |grep zygote , get the pid of zygote64
(Attention: zygote64 should never been killed or reboot,
otherwise we can get the tombstone file)
3 kill -5 pid of zygote64
4 cd data/tombstones/, and could find the tombstone file of
zygote64.
Change-Id: Ic152b081024d6c12f757927079fd221b63445b18
This commit only prints the raw value of the owner tag, pretty-printing
will come in a follow-up commit.
Test: debuggerd `pidof adbd`
Test: static_crasher fdsan_file + manual inspection of tombstone
Change-Id: Idb7375a12e410d5b51e6fcb6885d4beb20bccd0e
Pass the address of the fdsan table down to crash_dump so that we can
dump the fdsan table along with the open file descriptor list.
Test: debuggerd_test
Test: manually ran an old static_crasher
Change-Id: Icbac5487109f2db1e1061c4d46de11b016b299e3
We have a LOG(FATAL) that can potentially happen before we turn off
SIGABRT. Move the signal handler defusing to the very start of main.
Bug: http://b/77920633
Test: treehugger
Change-Id: I7a2f2a0f2bed16e54467388044eca254102aa6a0
Reduce the amount of time that a process remains paused by pausing its
threads, fetching their registers, and then performing unwinding on a
copy of its address space. This also works around a kernel change
that's in 4.9 that prevents ptrace from reading memory of processes
that we don't have immediate permissions to ptrace (even if we
previously ptraced them).
Bug: http://b/62112103
Bug: http://b/63989615
Test: treehugger
Change-Id: I7b9cc5dd8f54a354bc61f1bda0d2b7a8a55733c4
Nobody is looking at the mismatches, and it can cause problems
with tombstone parsers.
Also, fix the dump_header_info test and remove unused properties_fake.cpp.
Test: Ran unit tests, verified tombstones still work.
Change-Id: I4261646016b4e84b26a5aee72f3227f1ce48ec9a
Move libdebuggerd headers into their own directory for namespacing,
move some includes to the top of their implementing files, delete some
dead code.
Test: mma, treehugger
Change-Id: Ie4c44e32e2ab3bc678092899d257fd4ed634aa34
Instead of printing a useless "ptrace attach failed: strerror(EPERM)"
message, print the name and pid of a competing tracer when we fail to
attach because a process is already being ptraced.
Bug: http://b/31531918
Test: debuggerd_test32, debuggerd_test64 on aosp_angler
Test: strace -p `pidof surfaceflinger`; debuggerd -b surfaceflinger
Change-Id: Ifd3f80fe03de30ff38c0e0068560a7b12875f29d
In debuggerd, when dumping a tombstone, run the new unwinder and verify
the old and new unwinder are the same. If not, dump enough information
in the tombstones to figure out how to duplicate the failure.
Bug: 23762183
Test: Builds, ran and forced a mismatch and verified output.
Change-Id: Ia178bde64d67e623d4f35086ebda68aebbff0c3c
Some processes have lots of threads and minidebug-info. Unwinding
these can take more than the original two seconds.
Bug: 62828735
Test: m
Test: debuggerd_test
Test: adb shell kill -s 6 `pid system_server`
Change-Id: I0041bd01753135ef9d86783a3c6a5cbca1c5bbad
Don't pause the threads we're going to dump until after we're about to
fetch their backtraces.
Bug: http://b/62112103
Test: debuggerd_test
Change-Id: Id7ab0464842b35f98f3b3ebc42fb76161d8afbd2
Add some tracing to figure out where time is going during a dump.
Bug: http://b/62112103
Test: systrace.py sched freq idle bionic
Change-Id: Ic2a212beeb0bb0350b4d9c2cd7a4e70adc97752d
crash_dump inherits its signal mask from the thread that forked it,
which always has all of its signals blocked, now that sigchain respects
sa_mask.
Manually clear the signal mask, and reduce the timeout to a
still-generous 2 seconds.
Bug: http://b/38427757
Test: manually inserted sleep in crash_dump
Change-Id: If1c9adb68777b71fb19d9b0f47d6998733ed8f52
All intercept requests and crash dump requests must now specify a
dump_type, which can be one of kDebuggerdNativeBacktrace,
kDebuggerdTombstone or kDebuggerdJavaBacktrace. Each process can have
only one outstanding intercept registered at a time.
There's only one non-trivial change in this changeset; and that is
to crash_dump. We now pass the type of dump via a command line
argument instead of inferring it from the (resent) signal, this allows
us to connect to tombstoned before we wait for the signal as the
protocol requires.
Test: debuggerd_test
Change-Id: I189b215acfecd08ac52ab29117e3465da00e3a37
.. for ART and the frameworks to link against. In the new stack dumping
scheme (see related bug), the Java runtime will communicate with
tombstoned in order to obtain a FD to which it can write its traces.
Also move things around to separate headers that are private
implementation details from headers that constitute the public debuggerd
API. There are currently only three such headers :
- tombstoned/tombstoned.h
- debuggerd/client.h
- debuggerd/handler.h
Bug: 32064548
Test: make
Change-Id: If1b8578550e373d84828b180bbe585f1088d1aa3
Processes that don't have dumpable set to 1 cannot have their
process/thread names read by processes that don't have all of their
capabilities. Fetch these names in crash_dump before dropping
privileges.
Bug: http://b/36237221
Test: debuggerd_test
Test: debuggerd -b `pidof android.hardware.bluetooth@1.0-service`
Change-Id: I174769e7b3c1ea9f11f9c8cbdff83028a4225783
If a process that's getting dumped dies before crash_dump starts (e.g.
because seccomp immediately kills it after it execs crash_dump),
improve the error message to not just say "target died before we could
attach".
Bug: http://b/36077710
Test: inserted an exit in the handler, inspected output
Change-Id: I7d394c66d60d328b096b15654b3648e1ed711728
We already check our /proc/`getppid()` fd every time we attach a thread, so
these were unneeded at best. The one that happened after dropping
capabilities was actively wrong, though, because /proc/pid access
checks happen on every operation. (only on some kernels?)
Also, add a check that getppid() doesn't change after opening
/proc/getppid().
Bug: http://b/35241370
Test: debuggerd -b `pidof com.android.bluetooth`
Change-Id: I807439d8c2afd027f3c382face50167a8a7946c4
Do an in-process unwind for processes that have PR_SET_NO_NEW_PRIVS
enabled.
Bug: http://b/34684590
Test: debuggerd_test, killall -ABRT media.codec
Change-Id: I62562ec2c419d6643970100ab1cc0288982a1eed
Set and restore PR_SET_DUMPABLE when performing a dump, so that
processes that have it implicitly cleared (e.g. services that acquire
filesystem capabilities) still get crash dumps.
Bug: http://b/35174939
Test: debuggerd -b `pidof surfaceflinger`
Change-Id: Ife933c10086e546726dec12a7efa3f9cedfeea60
/proc/<pid>/fd is also limited by ptrace_may_access.
Test: manual inspection of "debuggerd -b `pidof zygote`"
Change-Id: I1a28c21c0438fe8729bd8e041c6b418d6a84c586
Reading /proc/<pid>/maps does a ptrace_may_access check, which will
fail if we have fewer capabilities than the target, even if we've
already ptraced it.
Bug: http://b/35070339
Test: debuggerd -b `pidof zygote`
Change-Id: I984a061022bd945a7950b88f6d579e1bd735e893
