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aesni: Avoid a potential out-of-bounds load in aes_encrypt_icm()

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Given a partial block at the end of a payload, aes_encrypt_icm() would
perform a 16-byte load of the residual into a temporary variable.  This
is unsafe in principle since the full block may cross a page boundary.
Fix the problem by copying the residual into a stack buffer first.

Reported by:	syzbot+b7e44cde9e2e89f0f6c9@syzkaller.appspotmail.com
Reported by:	syzbot+4b5eaf123a99456b5160@syzkaller.appspotmail.com
Reported by:	syzbot+70c74c1aa232633355ca@syzkaller.appspotmail.com
Reported by:	syzbot+2c663776a52828373d41@syzkaller.appspotmail.com
Reviewed by:	cem, jhb
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D31730
This commit is contained in:
Mark Johnston 2021-08-30 14:22:20 -04:00
parent 0637070b5b
commit 564b6aa7fc
1 changed files with 13 additions and 5 deletions
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18
sys/crypto/aesni/aesni_wrap.c
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@ -213,9 +213,10 @@ aesni_encrypt_icm(int rounds, const void *key_schedule, size_t len,
__m128i ctr5, ctr6, ctr7, ctr8;
__m128i BSWAP_EPI64;
__m128i tout[8];
__m128i block;
struct blocks8 *top;
const struct blocks8 *blks;
size_t i, cnt;
size_t i, cnt, resid;
BSWAP_EPI64 = _mm_set_epi8(8,9,10,11,12,13,14,15,0,1,2,3,4,5,6,7);
@ -273,12 +274,19 @@ aesni_encrypt_icm(int rounds, const void *key_schedule, size_t len,
to += AES_BLOCK_LEN;
}
/* handle remaining partial round */
if (len % AES_BLOCK_LEN != 0) {
/*
* Handle remaining partial round. Copy the remaining payload onto the
* stack to ensure that the full block can be loaded safely.
*/
resid = len % AES_BLOCK_LEN;
if (resid != 0) {
tmp1 = _mm_shuffle_epi8(ctr1, BSWAP_EPI64);
tot = aesni_enc(rounds - 1, key_schedule, tmp1);
tot = tot ^ _mm_loadu_si128((const __m128i *)from);
memcpy(to, &tot, len % AES_BLOCK_LEN);
block = _mm_setzero_si128();
memcpy(&block, from, resid);
tot = tot ^ _mm_loadu_si128(&block);
memcpy(to, &tot, resid);
explicit_bzero(&block, sizeof(block));
}
}