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| author | Christian Krinitsin <mail@krinitsin.com> | 2025-07-08 13:28:15 +0200 |
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| committer | Christian Krinitsin <mail@krinitsin.com> | 2025-07-08 13:28:28 +0200 |
| commit | 5aa276efcbd67f4300ca1a7f809c6e00aadb03da (patch) | |
| tree | 9b8f0e074014cda8d42f5a97a95bc25082d8b764 /results/classifier/zero-shot-user-mode/instruction/1878501 | |
| parent | 1a3c4faf4e0a25ed0b86e8739d5319a634cb9112 (diff) | |
| download | qemu-analysis-5aa276efcbd67f4300ca1a7f809c6e00aadb03da.tar.gz qemu-analysis-5aa276efcbd67f4300ca1a7f809c6e00aadb03da.zip | |
restructure results
Diffstat (limited to 'results/classifier/zero-shot-user-mode/instruction/1878501')
| -rw-r--r-- | results/classifier/zero-shot-user-mode/instruction/1878501 | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/results/classifier/zero-shot-user-mode/instruction/1878501 b/results/classifier/zero-shot-user-mode/instruction/1878501 new file mode 100644 index 000000000..3675688f5 --- /dev/null +++ b/results/classifier/zero-shot-user-mode/instruction/1878501 @@ -0,0 +1,37 @@ +instruction: 0.405 +runtime: 0.320 +syscall: 0.275 + + + +qemu-i386 does not define AT_SYSINFO + +qemu-i386 does not define the AT_SYSINFO auxval when running i386 Linux binaries. + +On most libcs, this is properly handled, but this is mandatory for the i686 Bionic (Android) libc or it will segfault. + +This is due to a blind assumption that getauxval(AT_SYSINFO) will return a valid function pointer: + +The code varies from version to version, but it looks like this: + +void *__libc_sysinfo; +// mangled as _Z19__libc_init_sysinfov +void __libc_init_sysinfo() { + bool dummy; + // __bionic_getauxval = getauxval + __libc_sysinfo = reinterpret_cast<void *>(__bionic_getauxval(AT_SYSINFO, dummy)); +} + +A simple way to reproduce is to compile a basic C program against the NDK: + +int main(void) { return 0; } + +$ i686-linux-android-clang -static empty.c -o empty +$ qemu-i386 -cpu max ./empty +qemu: uncaught target signal 11 (Segmentation fault) - core dumped +Segmentation fault + +The place where it segfaults is misleading: It will, at least on the current NDK, crash on __set_thread_area, this is due to it calling a function pointer to __libc_sysinfo returned by __kernel_syscall. + +QEMU 4.1.1 (aarch64) +Pixel 2 XL via Termux \ No newline at end of file |