From b24fe6b66b86e601c725d30f00c37e684b6395b6 Mon Sep 17 00:00:00 2001 From: Frediano Ziglio Date: Thu, 30 Apr 2020 10:19:09 +0100 Subject: [PATCH] quic: Avoid possible buffer overflow in find_bucket Proved by fuzzing the code. Signed-off-by: Frediano Ziglio Acked-by: Uri Lublin --- subprojects/spice-common/common//quic_family_tmpl.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/subprojects/spice-common/common/quic_family_tmpl.c +++ b/subprojects/spice-common/common/quic_family_tmpl.c @@ -105,7 +105,12 @@ static s_bucket *FNAME(find_bucket)(Chan spice_assert(val < (0x1U << BPC)); } - return channel->_buckets_ptrs[val]; + /* The and (&) here is to avoid buffer overflows in case of garbage or malicious + * attempts. Is much faster then using comparisons and save us from such situations. + * Note that on normal build the check above won't be compiled as this code path + * is pretty hot and would cause speed regressions. + */ + return channel->_buckets_ptrs[val & ((1U << BPC) - 1)]; } #undef FNAME -- GitLab