| Message ID | 20190923144612.29668-1-Jason@zx2c4.com |
|---|---|
| State | Not Applicable |
| Delegated to: | David Miller |
| Headers | show |
| Series | ipv6: Properly check reference count flag before taking reference | expand |
Hi, > 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> Reviewed-by: Petr Vorel <pvorel@suse.cz> NOTE: this change was added in d64a1f574a29 ("ipv6: honor RT6_LOOKUP_F_DST_NOREF in rule lookup logic") Kind regards, Petr > --- > 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); > }
Apparently even with this (certainly correct) patch attached, users are still experiencing problems. Bug hunting continues, and I'll report back if I figure something out.
On 9/23/19 8:06 AM, Petr Vorel wrote: > Hi, > >> 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> > > Reviewed-by: Petr Vorel <pvorel@suse.cz> > > NOTE: this change was added in d64a1f574a29 ("ipv6: honor RT6_LOOKUP_F_DST_NOREF in rule lookup logic") > > Kind regards, > Petr > This was fixed earlier I think https://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git/commit/?id=7b09c2d052db4b4ad0b27b97918b46a7746966fa >> --- >> 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); >> }
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); }
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(-)