diff options
| author | Eric Dumazet <edumazet@google.com> | 2016-11-28 06:26:49 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-12-10 19:07:24 +0100 |
| commit | 1a15519fdcdb0f908ad1a3785178f9e18a2ebedb (patch) | |
| tree | 6b45149fcc6fb391d5dc8bfe2e75b732dc5b2ee1 /net/dccp/ipv4.c | |
| parent | baaf0c65bc8ea9c7a404b09bc8cc3b8a1e4f18df (diff) | |
net/dccp: fix use-after-free in dccp_invalid_packet
[ Upstream commit 648f0c28df282636c0c8a7a19ca3ce5fc80a39c3 ]
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 861e1fa25d5e..0759f5b9180e 100644 --- a/net/dccp/ipv4.c +++ b/net/dccp/ipv4.c @@ -698,6 +698,7 @@ 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; @@ -719,18 +720,19 @@ 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 |