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netfilter: tproxy: bail out if IP has been disabled on the device
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syzbot reports:
general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
[..]
RIP: 0010:nf_tproxy_laddr4+0xb7/0x340 net/ipv4/netfilter/nf_tproxy_ipv4.c:62
Call Trace:
 nft_tproxy_eval_v4 net/netfilter/nft_tproxy.c:56 [inline]
 nft_tproxy_eval+0xa9a/0x1a00 net/netfilter/nft_tproxy.c:168

__in_dev_get_rcu() can return NULL, so check for this.

Reported-and-tested-by: syzbot+b94a6818504ea90d7661@syzkaller.appspotmail.com
Fixes: cc6eb43 ("tproxy: use the interface primary IP address as a default value for --on-ip")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Florian Westphal authored and ummakynes committed May 28, 2024
1 parent 33c563e commit 21a673b
Showing 1 changed file with 2 additions and 0 deletions.
2 changes: 2 additions & 0 deletions net/ipv4/netfilter/nf_tproxy_ipv4.c
Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,8 @@ __be32 nf_tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr)

laddr = 0;
indev = __in_dev_get_rcu(skb->dev);
if (!indev)
return daddr;

in_dev_for_each_ifa_rcu(ifa, indev) {
if (ifa->ifa_flags & IFA_F_SECONDARY)
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