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Add macro to disable address safety instrumentation

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fasthash_accum_cstring_aligned() uses a technique, found in various
strlen() implementations, to detect a string's NUL terminator by
reading a word at at time. That triggers failures when testing with
"-fsanitize=address", at least with frontend code. To enable using
this function anywhere, add a function attribute macro to disable
such testing.

Reviewed by Jeff Davis

Discussion: https://postgr.es/m/CANWCAZbwvp7oUEkbw-xP4L0_S_WNKq-J-ucP4RCNDPJnrakUPw%40mail.gmail.com
This commit is contained in:
John Naylor 2024-04-06 12:14:38 +07:00
parent 4b968e2027
commit db17594ad7
2 changed files with 17 additions and 1 deletions
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13
src/include/c.h
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@ -135,6 +135,19 @@
#define pg_nodiscard #define pg_nodiscard
#endif #endif
/*
* This macro will disable address safety instrumentation for a function
* when running with "-fsanitize=address". Think twice before using this!
*/
#if defined(__clang__) || __GNUC__ >= 8
#define pg_attribute_no_sanitize_address() __attribute__((no_sanitize("address")))
#elif __has_attribute(no_sanitize_address)
/* This would work for clang, but it's deprecated. */
#define pg_attribute_no_sanitize_address() __attribute__((no_sanitize_address))
#else
#define pg_attribute_no_sanitize_address()
#endif
/* /*
* Place this macro before functions that should be allowed to make misaligned * Place this macro before functions that should be allowed to make misaligned
* accesses. Think twice before using it on non-x86-specific code! * accesses. Think twice before using it on non-x86-specific code!

5
src/include/common/hashfn_unstable.h
View File

@ -213,8 +213,11 @@ fasthash_accum_cstring_unaligned(fasthash_state *hs, const char *str)
* *
* With an aligned pointer, we consume the string a word at a time. * With an aligned pointer, we consume the string a word at a time.
* Loading the word containing the NUL terminator cannot segfault since * Loading the word containing the NUL terminator cannot segfault since
* allocation boundaries are suitably aligned. * allocation boundaries are suitably aligned. To keep from setting
* off alarms with address sanitizers, exclude this function from
* such testing.
*/ */
pg_attribute_no_sanitize_address()
static inline size_t static inline size_t
fasthash_accum_cstring_aligned(fasthash_state *hs, const char *str) fasthash_accum_cstring_aligned(fasthash_state *hs, const char *str)
{ {