| Message ID | 20220625064722.3722045-1-edumazet@google.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 0fcae3c8b1b32d79cb4bbf841023757358fb0413 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net-next] ipmr: fix a lockdep splat in ipmr_rtm_dumplink() | expand |
Hello: This patch was applied to netdev/net-next.git (master) by David S. Miller <davem@davemloft.net>: On Sat, 25 Jun 2022 06:47:22 +0000 you wrote: > vif_dev_read() should be used from RCU protected sections only. > > ipmr_rtm_dumplink() is holding RTNL, so the data structures > can not be changed. > > syzbot reported: > > [...] Here is the summary with links: - [net-next] ipmr: fix a lockdep splat in ipmr_rtm_dumplink() https://git.kernel.org/netdev/net-next/c/0fcae3c8b1b3 You are awesome, thank you!
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c index f095b6c8100bd24262c949390b68865b8b3987c3..73651d17e51f31c8755da6ac3c1c2763a99b1117 100644 --- a/net/ipv4/ipmr.c +++ b/net/ipv4/ipmr.c @@ -2753,7 +2753,7 @@ static bool ipmr_fill_vif(struct mr_table *mrt, u32 vifid, struct sk_buff *skb) struct vif_device *vif; vif = &mrt->vif_table[vifid]; - vif_dev = vif_dev_read(vif); + vif_dev = rtnl_dereference(vif->dev); /* if the VIF doesn't exist just continue */ if (!vif_dev) return true;
vif_dev_read() should be used from RCU protected sections only. ipmr_rtm_dumplink() is holding RTNL, so the data structures can not be changed. syzbot reported: net/ipv4/ipmr.c:84 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by syz-executor.4/3068: stack backtrace: CPU: 1 PID: 3068 Comm: syz-executor.4 Not tainted 5.19.0-rc3-syzkaller-00565-g5d04b0b634bb #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 vif_dev_read net/ipv4/ipmr.c:84 [inline] vif_dev_read net/ipv4/ipmr.c:82 [inline] ipmr_fill_vif net/ipv4/ipmr.c:2756 [inline] ipmr_rtm_dumplink+0x1343/0x18c0 net/ipv4/ipmr.c:2866 netlink_dump+0x541/0xc20 net/netlink/af_netlink.c:2275 __netlink_dump_start+0x647/0x900 net/netlink/af_netlink.c:2380 netlink_dump_start include/linux/netlink.h:245 [inline] rtnetlink_rcv_msg+0x73e/0xc90 net/core/rtnetlink.c:6046 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2501 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x543/0x7f0 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x917/0xe10 net/netlink/af_netlink.c:1921 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:734 ____sys_sendmsg+0x334/0x810 net/socket.c:2489 ___sys_sendmsg+0xf3/0x170 net/socket.c:2543 __sys_sendmmsg+0x195/0x470 net/socket.c:2629 __do_sys_sendmmsg net/socket.c:2658 [inline] __se_sys_sendmmsg net/socket.c:2655 [inline] __x64_sys_sendmmsg+0x99/0x100 net/socket.c:2655 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7fefd8a89109 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fefd9ca6168 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007fefd8b9bf60 RCX: 00007fefd8a89109 RDX: 0000000004924b68 RSI: 0000000020000140 RDI: 0000000000000003 RBP: 00007fefd8ae305d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffc346febaf R14: 00007fefd9ca6300 R15: 0000000000022000 </TASK> Fixes: ebc3197963fc ("ipmr: add rcu protection over (struct vif_device)->dev") Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Eric Dumazet <edumazet@google.com> --- net/ipv4/ipmr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)