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  • Hash : 39ba0ee6
    Author : Andrzej Hunt
    Date : 2021-06-04T18:25:19

    zlib: slide_hash: add MSAN annotation to suppress known read from uninitialised memory slide_hash knowingly reads (possibly) uninitialised memory, see comment lower down about prev[n] potentially being garbage. In this case, the result is never used - so we don't care about MSAN complaining about this read. By adding the no_sanitize("memory") attribute, clients of zlib won't see this (unnecessary) error when building and running with MemorySanitizer. An alternative approach is for clients to build zlib with -fsanitize-ignorelist=... where the ignorelist contains something like 'fun:slide_hash'. But that's more work and needs to be redone for any and all CI systems running a given project with MSAN. Adding this annotation to zlib's sources is overall more convenient - but also won't affect non-MSAN builds. This specific issue was found while running git's test suite, but has also been reported by other clients, see e.g. #518.