Messages in this thread Patch in this message | | | Subject | Re: BUG: unable to handle kernel NULL pointer dereference in ipv6_select_ident | From | Eric Dumazet <> | Date | Wed, 21 Dec 2011 21:52:55 +0100 |
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Le mercredi 21 décembre 2011 à 21:28 +0100, Eric Dumazet a écrit : > Le mercredi 21 décembre 2011 à 20:05 +0000, Chris Boot a écrit : > > On 21/12/2011 18:00, Eric Dumazet wrote: > > > Le mercredi 21 décembre 2011 à 18:36 +0100, Eric Dumazet a écrit : > > > > > >> Good point, thats a different problem then, since 3.1 is not supposed to > > >> have this bug. > > >> > > >> It seems rt->rt6i_peer points to invalid memory in your crash. > > >> > > >> (RBX=00000000000001f4) > > >> > > >> 8b 83 a4 00 00 00 mov 0xa4(%rbx),%eax p->refcnt > > >> 1f4+a4 -> CR2=0000000000000298 > > >> > > > It would help if you can confirm latest linux tree can reproduce the > > > bug. > > > > Hi Eric, > > > > I just built a v3.2-rc6-140-gb9e26df with the same config as the Debian > > 3.1.0 kernel. I can reproduce the bug just as easily with this kernel as > > with the Debian kernel. Unfortunately I wasn't able to get an entire > > trace, for some reason it didn't appear to be printed to the serial port > > and hung after the (long) list of loaded kernel modules. The crash > > happens at the same offset: > > > > Thanks ! > > Oh well, br_netfilter fake_rtable strikes again. > > I'll cook a patch in a couple of minutes... >
Could you try following patch ?
Thanks !
include/net/dst.h | 1 + net/bridge/br_netfilter.c | 2 +- net/ipv4/route.c | 4 ++-- net/ipv6/ip6_output.c | 2 +- 4 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/include/net/dst.h b/include/net/dst.h index 6faec1a..75766b4 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -53,6 +53,7 @@ struct dst_entry { #define DST_NOHASH 0x0008 #define DST_NOCACHE 0x0010 #define DST_NOCOUNT 0x0020 +#define DST_NOPEER 0x0040 short error; short obsolete; diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c index d6ec372..5693e5f 100644 --- a/net/bridge/br_netfilter.c +++ b/net/bridge/br_netfilter.c @@ -141,7 +141,7 @@ void br_netfilter_rtable_init(struct net_bridge *br) rt->dst.dev = br->dev; rt->dst.path = &rt->dst; dst_init_metrics(&rt->dst, br_dst_default_metrics, true); - rt->dst.flags = DST_NOXFRM; + rt->dst.flags = DST_NOXFRM | DST_NOPEER; rt->dst.ops = &fake_dst_ops; } diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 46af623..7720403 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1271,7 +1271,7 @@ void __ip_select_ident(struct iphdr *iph, struct dst_entry *dst, int more) { struct rtable *rt = (struct rtable *) dst; - if (rt) { + if (rt && !(rt->dst.flags & DST_NOPEER)) { if (rt->peer == NULL) rt_bind_peer(rt, rt->rt_dst, 1); @@ -1282,7 +1282,7 @@ void __ip_select_ident(struct iphdr *iph, struct dst_entry *dst, int more) iph->id = htons(inet_getid(rt->peer, more)); return; } - } else + } else if (!rt) printk(KERN_DEBUG "rt_bind_peer(0) @%p\n", __builtin_return_address(0)); diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 84d0bd5..ec56271 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -603,7 +603,7 @@ void ipv6_select_ident(struct frag_hdr *fhdr, struct rt6_info *rt) static atomic_t ipv6_fragmentation_id; int old, new; - if (rt) { + if (rt && !(rt->dst.flags & DST_NOPEER)) { struct inet_peer *peer; if (!rt->rt6i_peer)
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