[Bridge] net/bridge: warning in br_fdb_find

Andrey Konovalov andreyknvl at google.com
Mon Feb 27 15:33:11 UTC 2017


Hi,

I'm getting a huge number of warning reports while fuzzing the kernel
with syzkaller.
Unfortunately they are not reproducible.

On commit e5d56efc97f8240d0b5d66c03949382b6d7e5570 (Feb 26).

My .config is attached.

WARNING: CPU: 1 PID: 6203 at net/bridge/br_fdb.c:109
br_fdb_find+0x20c/0x220 net/bridge/br_fdb.c:109
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 6203 Comm: syz-executor0 Not tainted 4.10.0+ #54
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:15 [inline]
 dump_stack+0x292/0x398 lib/dump_stack.c:51
 panic+0x1cb/0x3a9 kernel/panic.c:179
 __warn+0x1c4/0x1e0 kernel/panic.c:540
 warn_slowpath_null+0x2c/0x40 kernel/panic.c:583
 br_fdb_find+0x20c/0x220 net/bridge/br_fdb.c:109
 fdb_insert+0xf7/0x300 net/bridge/br_fdb.c:529
 br_fdb_insert+0x3a/0x60 net/bridge/br_fdb.c:557
 __vlan_add+0x1621/0x3670 net/bridge/br_vlan.c:250
 br_vlan_add+0x9e1/0xf30 net/bridge/br_vlan.c:599
 br_vlan_init+0x241/0x320 net/bridge/br_vlan.c:940
 br_dev_init+0xe2/0x220 net/bridge/br_device.c:106
 register_netdevice+0x2f1/0xee0 net/core/dev.c:7137
 register_netdev+0x1a/0x30 net/core/dev.c:7313
 br_add_bridge+0x97/0xd0 net/bridge/br_if.c:393
 br_ioctl_deviceless_stub+0x800/0xa40 net/bridge/br_ioctl.c:378
 sock_ioctl+0x256/0x440 net/socket.c:960
 vfs_ioctl fs/ioctl.c:43 [inline]
 do_vfs_ioctl+0x1bf/0x1780 fs/ioctl.c:683
 SYSC_ioctl fs/ioctl.c:698 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:689
 entry_SYSCALL_64_fastpath+0x1f/0xc2
RIP: 0033:0x4458b9
RSP: 002b:00007f4afad8fb58 EFLAGS: 00000286 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00000000004458b9
RDX: 0000000020000000 RSI: 01400000000089a0 RDI: 0000000000000005
RBP: 00000000006e0be0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000286 R12: 0000000000708000
R13: 0000000000000010 R14: 0000000000080003 R15: 0000000000000000
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..
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