https://bugs.kde.org/show_bug.cgi?id=360571
Bug ID: 360571
Summary: Error about the Android Runtime reading below the
stack pointer on ARM
Product: valgrind
Version: 3.11.0
Platform: Android
OS: unspecified
Status: UNCONFIRMED
Severity: normal
Priority: NOR
Component: memcheck
Assignee: jsew...@acm.org
Reporter: anton.kiri...@linaro.org
The Android Runtime (ART) uses reads below the stack pointer (combined with a
guard memory region) to detect stack overflow, and as a result when an
application is run in the virtual machine, Valgrind outputs a lot of warnings
such as:
==29768== Invalid read of size 4
==29768== at 0x739AEBE0: ??? (in
/data/dalvik-cache/arm/system@framew...@boot.oat)
==29768== Address 0xfe96fdb0 is on thread 1's stack
==29768== 8192 bytes below stack pointer
==29768==
The assembly language code that is emitted by ART at the beginning of each
method, and that causes the warning, looks like this:
sub r12, sp, #8192
ldr.w r12, [r12, #0]
The --workaround-gcc296-bugs command-line parameter is supposed to help, but it
has some problems - it forces Valgrind to ignore memory accesses that are up to
1 KB below SP, but on ARM the distance is 8 KB.
I have seen the issue with a build of the master branch of the Android Open
Source Project, but is reproducible on older versions as well (e.g. the 6.0
release).
Reproducible: Always
Steps to Reproduce:
1. Install Valgrind on the Android device as documented in the README.android
file; assume that the installation directory is /data/local/tmp/valgrind.
2. Get an APK or a DEX file; let its name be Test.dex, and let the name of the
class containing the main() method be Test as well.
3. adb push Test.dex /data/local/tmp
4. adb shell /data/local/tmp/valgrind/bin/valgrind --workaround-gcc296-bugs
dalvikvm -cp /data/local/tmp/Test.dex Test
Actual Results:
Warnings similar to the one above are displayed.
Expected Results:
No warnings of that type are shown.
Currently, the workaround that I have been using is manually patching the
Valgrind source code (in particular, the VG_GCC296_BUG_STACK_SLOP constant in
memcheck/mc_errors.c), but a better solution is to introduce a way to configure
that value at runtime. Furthermore, I'd like to suggest an addition to the
README.android file - mentioning that people who want to run apps in the
virtual machine with Valgrind should use the --workaround-gcc296-bugs
parameter. Finally, that argument should perhaps be renamed to something more
accurate.
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