People are reporting that WireGuard experiences erratic crashes on 5.3, and bisected it down to 7d30a7f6424e. Casually flipping through that commit I noticed that a flag is checked using `|` instead of `&`, which in this current case, means that a reference is never incremented, which would result in the use-after-free users are seeing. This commit changes the `|` to the proper `&` test.
Cc: stable@vger.kernel.org Fixes: 7d30a7f6424e ("Merge branch 'ipv6-avoid-taking-refcnt-on-dst-during-route-lookup'") Signed-off-by: Jason A. Donenfeld Jason@zx2c4.com --- net/ipv6/ip6_fib.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index 87f47bc55c5e..6e2af411cd9c 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -318,7 +318,7 @@ struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6, if (rt->dst.error == -EAGAIN) { ip6_rt_put_flags(rt, flags); rt = net->ipv6.ip6_null_entry; - if (!(flags | RT6_LOOKUP_F_DST_NOREF)) + if (!(flags & RT6_LOOKUP_F_DST_NOREF)) dst_hold(&rt->dst); }