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ip4_reass: fix double-free of pbuf and wrong ip_reass_pbufcount

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This was broken by commit f1072fee8a on 07/28/17 when trying to fix bug #51595
This commit is contained in:
goldsimon 2018-01-09 08:19:03 +01:00
parent efa90d4294
commit 0795e289eb
1 changed files with 7 additions and 13 deletions
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20
src/core/ipv4/ip4_frag.c
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@ -345,7 +345,7 @@ ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata *ipr, struct
{ {
struct ip_reass_helper *iprh, *iprh_tmp, *iprh_prev = NULL; struct ip_reass_helper *iprh, *iprh_tmp, *iprh_prev = NULL;
struct pbuf *q; struct pbuf *q;
u16_t offset, len, clen; u16_t offset, len;
u8_t hlen; u8_t hlen;
struct ip_hdr *fraghdr; struct ip_hdr *fraghdr;
int valid = 1; int valid = 1;
@ -356,7 +356,7 @@ ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata *ipr, struct
hlen = IPH_HL_BYTES(fraghdr); hlen = IPH_HL_BYTES(fraghdr);
if (hlen > len) { if (hlen > len) {
/* invalid datagram */ /* invalid datagram */
goto freepbuf; return IP_REASS_VALIDATE_PBUF_DROPPED;
} }
len = (u16_t)(len - hlen); len = (u16_t)(len - hlen);
offset = IPH_OFFSET_BYTES(fraghdr); offset = IPH_OFFSET_BYTES(fraghdr);
@ -372,7 +372,7 @@ ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata *ipr, struct
iprh->end = (u16_t)(offset + len); iprh->end = (u16_t)(offset + len);
if (iprh->end < offset) { if (iprh->end < offset) {
/* u16_t overflow, cannot handle this */ /* u16_t overflow, cannot handle this */
goto freepbuf; return IP_REASS_VALIDATE_PBUF_DROPPED;
} }
/* Iterate through until we either get to the end of the list (append), /* Iterate through until we either get to the end of the list (append),
@ -387,7 +387,7 @@ ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata *ipr, struct
#if IP_REASS_CHECK_OVERLAP #if IP_REASS_CHECK_OVERLAP
if ((iprh->start < iprh_prev->end) || (iprh->end > iprh_tmp->start)) { if ((iprh->start < iprh_prev->end) || (iprh->end > iprh_tmp->start)) {
/* fragment overlaps with previous or following, throw away */ /* fragment overlaps with previous or following, throw away */
goto freepbuf; return IP_REASS_VALIDATE_PBUF_DROPPED;
} }
#endif /* IP_REASS_CHECK_OVERLAP */ #endif /* IP_REASS_CHECK_OVERLAP */
iprh_prev->next_pbuf = new_p; iprh_prev->next_pbuf = new_p;
@ -400,7 +400,7 @@ ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata *ipr, struct
#if IP_REASS_CHECK_OVERLAP #if IP_REASS_CHECK_OVERLAP
if (iprh->end > iprh_tmp->start) { if (iprh->end > iprh_tmp->start) {
/* fragment overlaps with following, throw away */ /* fragment overlaps with following, throw away */
goto freepbuf; return IP_REASS_VALIDATE_PBUF_DROPPED;
} }
#endif /* IP_REASS_CHECK_OVERLAP */ #endif /* IP_REASS_CHECK_OVERLAP */
/* fragment with the lowest offset */ /* fragment with the lowest offset */
@ -409,11 +409,11 @@ ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata *ipr, struct
break; break;
} else if (iprh->start == iprh_tmp->start) { } else if (iprh->start == iprh_tmp->start) {
/* received the same datagram twice: no need to keep the datagram */ /* received the same datagram twice: no need to keep the datagram */
goto freepbuf; return IP_REASS_VALIDATE_PBUF_DROPPED;
#if IP_REASS_CHECK_OVERLAP #if IP_REASS_CHECK_OVERLAP
} else if (iprh->start < iprh_tmp->end) { } else if (iprh->start < iprh_tmp->end) {
/* overlap: no need to keep the new datagram */ /* overlap: no need to keep the new datagram */
goto freepbuf; return IP_REASS_VALIDATE_PBUF_DROPPED;
#endif /* IP_REASS_CHECK_OVERLAP */ #endif /* IP_REASS_CHECK_OVERLAP */
} else { } else {
/* Check if the fragments received so far have no holes. */ /* Check if the fragments received so far have no holes. */
@ -491,12 +491,6 @@ ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata *ipr, struct
} }
/* If we come here, not all fragments were received, yet! */ /* If we come here, not all fragments were received, yet! */
return IP_REASS_VALIDATE_PBUF_QUEUED; /* not yet valid! */ return IP_REASS_VALIDATE_PBUF_QUEUED; /* not yet valid! */
freepbuf:
clen = pbuf_clen(new_p);
LWIP_ASSERT("ip_reass_pbufcount >= clen", ip_reass_pbufcount >= clen);
ip_reass_pbufcount = (u16_t)(ip_reass_pbufcount - clen);
pbuf_free(new_p);
return IP_REASS_VALIDATE_PBUF_DROPPED;
} }
/** /**