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[sanitizer] Fix prctl interceptor causing PAC authentication failure #153081

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Merged
merged 1 commit into from
Sep 3, 2025
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[sanitizer] Fix prctl interceptor causing PAC authentication failure #153081

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32 changes: 29 additions & 3 deletions compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
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Original file line number Diff line number Diff line change
Expand Up @@ -1285,8 +1285,34 @@ INTERCEPTOR(int, puts, char *s) {
#endif

#if SANITIZER_INTERCEPT_PRCTL
INTERCEPTOR(int, prctl, int option, unsigned long arg2, unsigned long arg3,
unsigned long arg4, unsigned long arg5) {

# if defined(__aarch64__)
// https://llvm.org/docs/PointerAuth.html
// AArch64 is currently the only architecture with full PAC support.
// Avoid adding PAC instructions to prevent crashes caused by
// prctl(PR_PAC_RESET_KEYS, ...). Since PR_PAC_RESET_KEYS resets the
// authentication key, using the old key afterward will lead to a crash.

# if defined(__ARM_FEATURE_BTI_DEFAULT)
# define BRANCH_PROTECTION_ATTRIBUTE \
__attribute__((target("branch-protection=bti")))
# else
# define BRANCH_PROTECTION_ATTRIBUTE \
__attribute__((target("branch-protection=none")))
# endif

# define PRCTL_INTERCEPTOR(ret_type, func, ...) \
DEFINE_REAL(ret_type, func, __VA_ARGS__) \
DECLARE_WRAPPER(ret_type, func, __VA_ARGS__) \
extern "C" INTERCEPTOR_ATTRIBUTE BRANCH_PROTECTION_ATTRIBUTE ret_type \
WRAP(func)(__VA_ARGS__)

# else
# define PRCTL_INTERCEPTOR INTERCEPTOR
# endif

PRCTL_INTERCEPTOR(int, prctl, int option, unsigned long arg2,
unsigned long arg3, unsigned long arg4, unsigned long arg5) {
void *ctx;
COMMON_INTERCEPTOR_ENTER(ctx, prctl, option, arg2, arg3, arg4, arg5);
static const int PR_SET_NAME = 15;
Expand Down Expand Up @@ -1326,7 +1352,7 @@ INTERCEPTOR(int, prctl, int option, unsigned long arg2, unsigned long arg3,
}
return res;
}
#define INIT_PRCTL COMMON_INTERCEPT_FUNCTION(prctl)
# define INIT_PRCTL COMMON_INTERCEPT_FUNCTION(prctl)
#else
#define INIT_PRCTL
#endif // SANITIZER_INTERCEPT_PRCTL
Expand Down
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