From: Paolo Abeni pabeni@redhat.com
[ Upstream commit c329b261afe71197d9da83c1f18eb45a7e97e089 ]
Ian reported several skb corruptions triggered by rx-gro-list, collecting different oops alike:
[ 62.624003] BUG: kernel NULL pointer dereference, address: 00000000000000c0 [ 62.631083] #PF: supervisor read access in kernel mode [ 62.636312] #PF: error_code(0x0000) - not-present page [ 62.641541] PGD 0 P4D 0 [ 62.644174] Oops: 0000 [#1] PREEMPT SMP NOPTI [ 62.648629] CPU: 1 PID: 913 Comm: napi/eno2-79 Not tainted 6.4.0 #364 [ 62.655162] Hardware name: Supermicro Super Server/A2SDi-12C-HLN4F, BIOS 1.7a 10/13/2022 [ 62.663344] RIP: 0010:__udp_gso_segment (./include/linux/skbuff.h:2858 ./include/linux/udp.h:23 net/ipv4/udp_offload.c:228 net/ipv4/udp_offload.c:261 net/ipv4/udp_offload.c:277) [ 62.687193] RSP: 0018:ffffbd3a83b4f868 EFLAGS: 00010246 [ 62.692515] RAX: 00000000000000ce RBX: 0000000000000000 RCX: 0000000000000000 [ 62.699743] RDX: ffffa124def8a000 RSI: 0000000000000079 RDI: ffffa125952a14d4 [ 62.706970] RBP: ffffa124def8a000 R08: 0000000000000022 R09: 00002000001558c9 [ 62.714199] R10: 0000000000000000 R11: 00000000be554639 R12: 00000000000000e2 [ 62.721426] R13: ffffa125952a1400 R14: ffffa125952a1400 R15: 00002000001558c9 [ 62.728654] FS: 0000000000000000(0000) GS:ffffa127efa40000(0000) knlGS:0000000000000000 [ 62.736852] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 62.742702] CR2: 00000000000000c0 CR3: 00000001034b0000 CR4: 00000000003526e0 [ 62.749948] Call Trace: [ 62.752498] <TASK> [ 62.779267] inet_gso_segment (net/ipv4/af_inet.c:1398) [ 62.787605] skb_mac_gso_segment (net/core/gro.c:141) [ 62.791906] __skb_gso_segment (net/core/dev.c:3403 (discriminator 2)) [ 62.800492] validate_xmit_skb (./include/linux/netdevice.h:4862 net/core/dev.c:3659) [ 62.804695] validate_xmit_skb_list (net/core/dev.c:3710) [ 62.809158] sch_direct_xmit (net/sched/sch_generic.c:330) [ 62.813198] __dev_queue_xmit (net/core/dev.c:3805 net/core/dev.c:4210) net/netfilter/core.c:626) [ 62.821093] br_dev_queue_push_xmit (net/bridge/br_forward.c:55) [ 62.825652] maybe_deliver (net/bridge/br_forward.c:193) [ 62.829420] br_flood (net/bridge/br_forward.c:233) [ 62.832758] br_handle_frame_finish (net/bridge/br_input.c:215) [ 62.837403] br_handle_frame (net/bridge/br_input.c:298 net/bridge/br_input.c:416) [ 62.851417] __netif_receive_skb_core.constprop.0 (net/core/dev.c:5387) [ 62.866114] __netif_receive_skb_list_core (net/core/dev.c:5570) [ 62.871367] netif_receive_skb_list_internal (net/core/dev.c:5638 net/core/dev.c:5727) [ 62.876795] napi_complete_done (./include/linux/list.h:37 ./include/net/gro.h:434 ./include/net/gro.h:429 net/core/dev.c:6067) [ 62.881004] ixgbe_poll (drivers/net/ethernet/intel/ixgbe/ixgbe_main.c:3191) [ 62.893534] __napi_poll (net/core/dev.c:6498) [ 62.897133] napi_threaded_poll (./include/linux/netpoll.h:89 net/core/dev.c:6640) [ 62.905276] kthread (kernel/kthread.c:379) [ 62.913435] ret_from_fork (arch/x86/entry/entry_64.S:314) [ 62.917119] </TASK>
In the critical scenario, rx-gro-list GRO-ed packets are fed, via a bridge, both to the local input path and to an egress device (tun).
The segmentation of such packets unsafely writes to the cloned skbs with shared heads.
This change addresses the issue by uncloning as needed the to-be-segmented skbs.
Reported-by: Ian Kumlien ian.kumlien@gmail.com Tested-by: Ian Kumlien ian.kumlien@gmail.com Fixes: 3a1296a38d0c ("net: Support GRO/GSO fraglist chaining.") Signed-off-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/skbuff.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index ef9772b12624c..b6c16db86c719 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4042,6 +4042,11 @@ struct sk_buff *skb_segment_list(struct sk_buff *skb,
skb_push(skb, -skb_network_offset(skb) + offset);
+ /* Ensure the head is writeable before touching the shared info */ + err = skb_unclone(skb, GFP_ATOMIC); + if (err) + goto err_linearize; + skb_shinfo(skb)->frag_list = NULL;
while (list_skb) {