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Eric Dumazet authored
Daniel Petre reported crashes in icmp_dst_unreach() with following call graph: #3 [ffff88003fc03938] __stack_chk_fail at ffffffff81037f77 #4 [ffff88003fc03948] icmp_send at ffffffff814d5fec #5 [ffff88003fc03ae8] ipv4_link_failure at ffffffff814a1795 #6 [ffff88003fc03af8] ipgre_tunnel_xmit at ffffffff814e7965 #7 [ffff88003fc03b78] dev_hard_start_xmit at ffffffff8146e032 #8 [ffff88003fc03bc8] sch_direct_xmit at ffffffff81487d66 #9 [ffff88003fc03c08] __qdisc_run at ffffffff81487efd #10 [ffff88003fc03c48] dev_queue_xmit at ffffffff8146e5a7 #11 [ffff88003fc03c88] ip_finish_output at ffffffff814ab596 Daniel found a similar problem mentioned in http://lkml.indiana.edu/hypermail/linux/kernel/1007.0/00961.html And indeed this is the root cause : skb->cb[] contains data fooling IP stack. We must clear IPCB in ip_tunnel_xmit() sooner in case dst_link_failure() is called. Or else skb->cb[] might contain garbage from GSO segmentation layer. A similar fix was tested on linux-3.9, but gre code was refactored in linux-3.10. I'll send patches for stable kernels as well. Many thanks to Daniel for providing reports, patches and testing ! Reported-by: Daniel Petre <daniel.petre@rcs-rds.ro> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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