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- libsanitizer: enable getauxval() on uClibc-ng
- uClibc-ng has provided getauxval() since 1.0.41 (commit d869bb1, 2022-12)
- but cannot satisfy __GLIBC_PREREQ(2, 16) because it deliberately reports
- __GLIBC__=2 / __GLIBC_MINOR__=2 for source compatibility. As a result
- SANITIZER_USE_GETAUXVAL evaluates to 0 on uClibc-ng and GetPageSize()
- falls back to sysconf(_SC_PAGESIZE).
- That sysconf() call is not safe to make from libsanitizer's .init_array
- constructor (runs before libc is fully initialized) and can return 0,
- which makes ReadFileToBuffer compute kMinFileLen = 0 and call
- MmapOrDie(0) -- the kernel rejects mmap(NULL, 0, ...) with EINVAL:
- ==NN==ERROR: AddressSanitizer failed to allocate 0x0 (0) bytes of
- ReadFileToBuffer (error code: 22)
- ERROR: Failed to mmap
- Add SANITIZER_UCLIBC to the SANITIZER_USE_GETAUXVAL activation predicate
- so libsanitizer uses uClibc-ng's getauxval() directly. This also gives
- correct AT_EXECFN (symbolizer) and AT_BASE (LSan) values via the
- auxiliary vector instead of the unsafe sysconf()/proc-based fallbacks.
- SANITIZER_UCLIBC is provided by the earlier
- 0001-libsanitizer-do-not-treat-uClibc-ng-as-glibc.patch and
- sanitizer_getauxval.h already includes sanitizer_platform.h, so the
- macro is in scope here.
- Signed-off-by: Ramin Moussavi <ramin.moussavi@yacoub.de>
- ---
- --- a/libsanitizer/sanitizer_common/sanitizer_getauxval.h
- +++ b/libsanitizer/sanitizer_common/sanitizer_getauxval.h
- @@ -21,7 +21,8 @@
- #if SANITIZER_LINUX || SANITIZER_FUCHSIA
-
- # if (__GLIBC_PREREQ(2, 16) || (SANITIZER_ANDROID && __ANDROID_API__ >= 21) || \
- - SANITIZER_FUCHSIA) && \
- + SANITIZER_FUCHSIA || \
- + SANITIZER_UCLIBC) && \
- !SANITIZER_GO
- # define SANITIZER_USE_GETAUXVAL 1
- # else
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