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Check packet length to do not make out of bounds access. Also save ah_nxt

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value to use it later, since ah pointer can become invalid.

Reported by:	Maxime Villard <max at m00nbsd dot net>
MFC after:	5 days
This commit is contained in:
Andrey V. Elsukov 2018-02-19 11:14:38 +00:00
parent 8cebd0e419
commit 6ca39da354
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=329561
1 changed files with 14 additions and 1 deletions
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15
sys/netipsec/xform_ah.c
View file

@ -582,6 +582,16 @@ ah_input(struct mbuf *m, struct secasvar *sav, int skip, int protoff)
error = EACCES;
goto bad;
}
if (skip + authsize + rplen > m->m_pkthdr.len) {
DPRINTF(("%s: bad mbuf length %u (expecting %lu)"
" for packet in SA %s/%08lx\n", __func__,
m->m_pkthdr.len, (u_long) (skip + authsize + rplen),
ipsec_address(&sav->sah->saidx.dst, buf, sizeof(buf)),
(u_long) ntohl(sav->spi)));
AHSTAT_INC(ahs_badauthl);
error = EACCES;
goto bad;
}
AHSTAT_ADD(ahs_ibytes, m->m_pkthdr.len - skip - hl);
/* Get crypto descriptors. */
@ -626,6 +636,9 @@ ah_input(struct mbuf *m, struct secasvar *sav, int skip, int protoff)
/* Zeroize the authenticator on the packet. */
m_copyback(m, skip + rplen, authsize, ipseczeroes);
/* Save ah_nxt, since ah pointer can become invalid after "massage" */
hl = ah->ah_nxt;
/* "Massage" the packet headers for crypto processing. */
error = ah_massage_headers(&m, sav->sah->saidx.dst.sa.sa_family,
skip, ahx->type, 0);
@ -650,7 +663,7 @@ ah_input(struct mbuf *m, struct secasvar *sav, int skip, int protoff)
/* These are passed as-is to the callback. */
xd->sav = sav;
xd->nxt = ah->ah_nxt;
xd->nxt = hl;
xd->protoff = protoff;
xd->skip = skip;
xd->cryptoid = cryptoid;