4.20-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit 2a5ff07a0eb945f291e361aa6f6becca8340ba46 ]
We keep receiving syzbot reports [1] that show that tunnels do not play the rcu/IFF_UP rules properly.
At device dismantle phase, gro_cells_destroy() will be called only after a full rcu grace period is observed after IFF_UP has been cleared.
This means that IFF_UP needs to be tested before queueing packets into netif_rx() or gro_cells.
This patch implements the test in gro_cells_receive() because too many callers do not seem to bother enough.
[1] BUG: unable to handle kernel paging request at fffff4ca0b9ffffe PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 21 Comm: kworker/u4:1 Not tainted 5.0.0+ #97 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: netns cleanup_net RIP: 0010:__skb_unlink include/linux/skbuff.h:1929 [inline] RIP: 0010:__skb_dequeue include/linux/skbuff.h:1945 [inline] RIP: 0010:__skb_queue_purge include/linux/skbuff.h:2656 [inline] RIP: 0010:gro_cells_destroy net/core/gro_cells.c:89 [inline] RIP: 0010:gro_cells_destroy+0x19d/0x360 net/core/gro_cells.c:78 Code: 03 42 80 3c 20 00 0f 85 53 01 00 00 48 8d 7a 08 49 8b 47 08 49 c7 07 00 00 00 00 48 89 f9 49 c7 47 08 00 00 00 00 48 c1 e9 03 <42> 80 3c 21 00 0f 85 10 01 00 00 48 89 c1 48 89 42 08 48 c1 e9 03 RSP: 0018:ffff8880aa3f79a8 EFLAGS: 00010a02 RAX: 00ffffffffffffe8 RBX: ffffe8ffffc64b70 RCX: 1ffff8ca0b9ffffe RDX: ffffc6505cffffe8 RSI: ffffffff858410ca RDI: ffffc6505cfffff0 RBP: ffff8880aa3f7a08 R08: ffff8880aa3e8580 R09: fffffbfff1263645 R10: fffffbfff1263644 R11: ffffffff8931b223 R12: dffffc0000000000 R13: 0000000000000000 R14: ffffe8ffffc64b80 R15: ffffe8ffffc64b75 kobject: 'loop2' (000000004bd7d84a): kobject_uevent_env FS: 0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffff4ca0b9ffffe CR3: 0000000094941000 CR4: 00000000001406f0 Call Trace: kobject: 'loop2' (000000004bd7d84a): fill_kobj_path: path = '/devices/virtual/block/loop2' ip_tunnel_dev_free+0x19/0x60 net/ipv4/ip_tunnel.c:1010 netdev_run_todo+0x51c/0x7d0 net/core/dev.c:8970 rtnl_unlock+0xe/0x10 net/core/rtnetlink.c:116 ip_tunnel_delete_nets+0x423/0x5f0 net/ipv4/ip_tunnel.c:1124 vti_exit_batch_net+0x23/0x30 net/ipv4/ip_vti.c:495 ops_exit_list.isra.0+0x105/0x160 net/core/net_namespace.c:156 cleanup_net+0x3fb/0x960 net/core/net_namespace.c:551 process_one_work+0x98e/0x1790 kernel/workqueue.c:2173 worker_thread+0x98/0xe40 kernel/workqueue.c:2319 kthread+0x357/0x430 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352 Modules linked in: CR2: fffff4ca0b9ffffe [ end trace 513fc9c1338d1cb3 ] RIP: 0010:__skb_unlink include/linux/skbuff.h:1929 [inline] RIP: 0010:__skb_dequeue include/linux/skbuff.h:1945 [inline] RIP: 0010:__skb_queue_purge include/linux/skbuff.h:2656 [inline] RIP: 0010:gro_cells_destroy net/core/gro_cells.c:89 [inline] RIP: 0010:gro_cells_destroy+0x19d/0x360 net/core/gro_cells.c:78 Code: 03 42 80 3c 20 00 0f 85 53 01 00 00 48 8d 7a 08 49 8b 47 08 49 c7 07 00 00 00 00 48 89 f9 49 c7 47 08 00 00 00 00 48 c1 e9 03 <42> 80 3c 21 00 0f 85 10 01 00 00 48 89 c1 48 89 42 08 48 c1 e9 03 RSP: 0018:ffff8880aa3f79a8 EFLAGS: 00010a02 RAX: 00ffffffffffffe8 RBX: ffffe8ffffc64b70 RCX: 1ffff8ca0b9ffffe RDX: ffffc6505cffffe8 RSI: ffffffff858410ca RDI: ffffc6505cfffff0 RBP: ffff8880aa3f7a08 R08: ffff8880aa3e8580 R09: fffffbfff1263645 R10: fffffbfff1263644 R11: ffffffff8931b223 R12: dffffc0000000000 kobject: 'loop3' (00000000e4ee57a6): kobject_uevent_env R13: 0000000000000000 R14: ffffe8ffffc64b80 R15: ffffe8ffffc64b75 FS: 0000000000000000(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffff4ca0b9ffffe CR3: 0000000094941000 CR4: 00000000001406f0
Fixes: c9e6bc644e55 ("net: add gro_cells infrastructure") Signed-off-by: Eric Dumazet edumazet@google.com Reported-by: syzbot syzkaller@googlegroups.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/core/gro_cells.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-)
--- a/net/core/gro_cells.c +++ b/net/core/gro_cells.c @@ -13,22 +13,36 @@ int gro_cells_receive(struct gro_cells * { struct net_device *dev = skb->dev; struct gro_cell *cell; + int res;
- if (!gcells->cells || skb_cloned(skb) || netif_elide_gro(dev)) - return netif_rx(skb); + rcu_read_lock(); + if (unlikely(!(dev->flags & IFF_UP))) + goto drop; + + if (!gcells->cells || skb_cloned(skb) || netif_elide_gro(dev)) { + res = netif_rx(skb); + goto unlock; + }
cell = this_cpu_ptr(gcells->cells);
if (skb_queue_len(&cell->napi_skbs) > netdev_max_backlog) { +drop: atomic_long_inc(&dev->rx_dropped); kfree_skb(skb); - return NET_RX_DROP; + res = NET_RX_DROP; + goto unlock; }
__skb_queue_tail(&cell->napi_skbs, skb); if (skb_queue_len(&cell->napi_skbs) == 1) napi_schedule(&cell->napi); - return NET_RX_SUCCESS; + + res = NET_RX_SUCCESS; + +unlock: + rcu_read_unlock(); + return res; } EXPORT_SYMBOL(gro_cells_receive);