diff options
| author | Eric Dumazet <edumazet@google.com> | 2016-11-28 06:26:49 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-11-29 20:37:26 -0500 |
| commit | 648f0c28df282636c0c8a7a19ca3ce5fc80a39c3 (patch) | |
| tree | 21a521e1c65060e4ef3060e122915134c29aa931 /net/dccp/ipv4.c | |
| parent | ffac0e967f20b7637936dbaa21df08c55f672604 (diff) | |
net/dccp: fix use-after-free in dccp_invalid_packet
pskb_may_pull() can reallocate skb->head, we need to reload dh pointer
in dccp_invalid_packet() or risk use after free.
Bug found by Andrey Konovalov using syzkaller.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/dccp/ipv4.c')
| -rw-r--r-- | net/dccp/ipv4.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c index b567c8725aea..edbe59d203ef 100644 --- a/net/dccp/ipv4.c +++ b/net/dccp/ipv4.c @@ -700,6 +700,7 @@ int dccp_invalid_packet(struct sk_buff *skb) { const struct dccp_hdr *dh; unsigned int cscov; + u8 dccph_doff; if (skb->pkt_type != PACKET_HOST) return 1; @@ -721,18 +722,19 @@ int dccp_invalid_packet(struct sk_buff *skb) /* * If P.Data Offset is too small for packet type, drop packet and return */ - if (dh->dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { - DCCP_WARN("P.Data Offset(%u) too small\n", dh->dccph_doff); + dccph_doff = dh->dccph_doff; + if (dccph_doff < dccp_hdr_len(skb) / sizeof(u32)) { + DCCP_WARN("P.Data Offset(%u) too small\n", dccph_doff); return 1; } /* * If P.Data Offset is too too large for packet, drop packet and return */ - if (!pskb_may_pull(skb, dh->dccph_doff * sizeof(u32))) { - DCCP_WARN("P.Data Offset(%u) too large\n", dh->dccph_doff); + if (!pskb_may_pull(skb, dccph_doff * sizeof(u32))) { + DCCP_WARN("P.Data Offset(%u) too large\n", dccph_doff); return 1; } - + dh = dccp_hdr(skb); /* * If P.type is not Data, Ack, or DataAck and P.X == 0 (the packet * has short sequence numbers), drop packet and return |