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The zlib inflate code has an old micro-optimization based on the assumption that for pre-increment memory accesses, the compiler will generate code that fits better into the processor's pipeline than what would be generated for post-increment memory accesses. This optimization was already removed in upstream zlib in 2016: https://github.com/madler/zlib/commit/9aaec95e8211 This optimization causes UB according to C99, which says in section 6.5.6 "Additive operators": "If both the pointer operand and the result point to elements of the same array object, or one past the last element of the array object, the evaluation shall not produce an overflow; otherwise, the behavior is undefined". This UB is not only a theoretical concern, but can also cause trouble for future work on compiler-based sanitizers. According to the zlib commit, this optimization also is not optimal anymore with modern compilers. Replace uses of OFF, PUP and UP_UNALIGNED with their definitions in the POSTINC case, and remove the macro definitions, just like in the upstream patch. Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Mikhail Zaslonko <zaslonko@linux.ibm.com> Link: http://lkml.kernel.org/r/20200507123112.252723-1-jannh@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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| .. | ||
| inffast.c | ||
| inffast.h | ||
| inffixed.h | ||
| inflate_syms.c | ||
| inflate.c | ||
| inflate.h | ||
| inftrees.c | ||
| inftrees.h | ||
| infutil.c | ||
| infutil.h | ||
| Makefile | ||