diff options
| author | Florian Westphal <fw@strlen.de> | 2018-12-11 07:45:29 +0100 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2018-12-13 00:58:22 +0100 |
| commit | 542fbda0f08f1cbbc250f9e59f7537649651d0c8 (patch) | |
| tree | 9926197367cf68cd1c82f06e6276585bd25c02a7 /net | |
| parent | 708abf74dd87f8640871b814faa195fb5970b0e3 (diff) | |
| download | linux-542fbda0f08f1cbbc250f9e59f7537649651d0c8.tar.bz2 | |
netfilter: nat: can't use dst_hold on noref dst
The dst entry might already have a zero refcount, waiting on rcu list
to be free'd. Using dst_hold() transitions its reference count to 1, and
next dst release will try to free it again -- resulting in a double free:
WARNING: CPU: 1 PID: 0 at include/net/dst.h:239 nf_xfrm_me_harder+0xe7/0x130 [nf_nat]
RIP: 0010:nf_xfrm_me_harder+0xe7/0x130 [nf_nat]
Code: 48 8b 5c 24 60 65 48 33 1c 25 28 00 00 00 75 53 48 83 c4 68 5b 5d 41 5c c3 85 c0 74 0d 8d 48 01 f0 0f b1 0a 74 86 85 c0 75 f3 <0f> 0b e9 7b ff ff ff 29 c6 31 d2 b9 20 00 48 00 4c 89 e7 e8 31 27
Call Trace:
nf_nat_ipv4_out+0x78/0x90 [nf_nat_ipv4]
nf_hook_slow+0x36/0xd0
ip_output+0x9f/0xd0
ip_forward+0x328/0x440
ip_rcv+0x8a/0xb0
Use dst_hold_safe instead and bail out if we cannot take a reference.
Fixes: a4c2fd7f7891 ("net: remove DST_NOCACHE flag")
Reported-by: Martin Zaharinov <micron10@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/netfilter/nf_nat_core.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c index e2b196054dfc..2268b10a9dcf 100644 --- a/net/netfilter/nf_nat_core.c +++ b/net/netfilter/nf_nat_core.c @@ -117,7 +117,8 @@ int nf_xfrm_me_harder(struct net *net, struct sk_buff *skb, unsigned int family) dst = skb_dst(skb); if (dst->xfrm) dst = ((struct xfrm_dst *)dst)->route; - dst_hold(dst); + if (!dst_hold_safe(dst)) + return -EHOSTUNREACH; if (sk && !net_eq(net, sock_net(sk))) sk = NULL; |