Messages in this thread Patch in this message | | | From | Arvind Sankar <> | Subject | [PATCH v4 1/6] crypto: lib/sha256 - Use memzero_explicit() for clearing state | Date | Sun, 25 Oct 2020 10:31:14 -0400 |
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Without the barrier_data() inside memzero_explicit(), the compiler may optimize away the state-clearing if it can tell that the state is not used afterwards. At least in lib/crypto/sha256.c:__sha256_final(), the function can get inlined into sha256(), in which case the memset is optimized away.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Reviewed-by: Eric Biggers <ebiggers@google.com> --- lib/crypto/sha256.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/crypto/sha256.c b/lib/crypto/sha256.c index 2321f6cb322f..d43bc39ab05e 100644 --- a/lib/crypto/sha256.c +++ b/lib/crypto/sha256.c @@ -265,7 +265,7 @@ static void __sha256_final(struct sha256_state *sctx, u8 *out, int digest_words) put_unaligned_be32(sctx->state[i], &dst[i]); /* Zeroize sensitive information. */ - memset(sctx, 0, sizeof(*sctx)); + memzero_explicit(sctx, sizeof(*sctx)); } void sha256_final(struct sha256_state *sctx, u8 *out) -- 2.26.2
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