Re: [syzbot] general protection fault in blk_mq_run_hw_queues

From: Guoqing Jiang
Date: Mon Jul 05 2021 - 02:01:06 EST


Hi,

On 7/5/21 1:48 PM, syzbot wrote:
Hello,

syzbot found the following issue on:

HEAD commit: dbe69e43 Merge tag 'net-next-5.14' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12690d94300000
kernel config: https://syzkaller.appspot.com/x/.config?x=ef0afdedbe2d773d
dashboard link: https://syzkaller.appspot.com/bug?extid=9ca43ff47167c0ee3466
compiler: Debian clang version 11.0.1-2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17ded6ac300000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12af1344300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9ca43ff47167c0ee3466@xxxxxxxxxxxxxxxxxxxxxxxxx

netlink: 4 bytes leftover after parsing attributes in process `syz-executor092'.
netlink: 4 bytes leftover after parsing attributes in process `syz-executor092'.
nbd: socks must be embedded in a SOCK_ITEM attr
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 8422 Comm: syz-executor092 Tainted: G W 5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:blk_mq_map_queue_type block/blk-mq.h:96 [inline]
RIP: 0010:blk_mq_get_sq_hctx block/blk-mq.c:1663 [inline]
RIP: 0010:blk_mq_run_hw_queues+0x14f/0x430 block/blk-mq.c:1682
Code: 80 3c 08 00 74 08 48 89 ef e8 0d 0f dd fd 44 89 fb 48 c1 e3 02 48 03 5d 00 48 89 d8 48 c1 e8 03 48 bd 00 00 00 00 00 fc ff df <8a> 04 28 84 c0 0f 85 b7 02 00 00 8b 03 49 8d 1c c4 48 89 d8 48 c1
RSP: 0018:ffffc9000183f160 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88801f912b38
RBP: dffffc0000000000 R08: ffffffff83eb6412 R09: ffffed1003f22687
R10: ffffed1003f22687 R11: 0000000000000000 R12: ffff88814615f4d8
R13: 0000000000000000 R14: ffff88801f912af0 R15: 0000000000000000
FS: 0000000001ab6300(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa915ace020 CR3: 0000000018231000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
blk_set_queue_dying block/blk-core.c:353 [inline]
blk_cleanup_queue+0x9c/0x220 block/blk-core.c:380
blk_cleanup_disk+0x3b/0x80 block/genhd.c:1324
nbd_dev_remove drivers/block/nbd.c:226 [inline]
nbd_put+0x9d/0x170 drivers/block/nbd.c:246
nbd_genl_connect+0x17e7/0x1aa0 drivers/block/nbd.c:1957
genl_family_rcv_msg_doit net/netlink/genetlink.c:739 [inline]
genl_family_rcv_msg net/netlink/genetlink.c:783 [inline]
genl_rcv_msg+0xfb4/0x13c0 net/netlink/genetlink.c:800
netlink_rcv_skb+0x1f0/0x460 net/netlink/af_netlink.c:2504
genl_rcv+0x24/0x40 net/netlink/genetlink.c:811
netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
netlink_unicast+0x7de/0x9b0 net/netlink/af_netlink.c:1340
netlink_sendmsg+0xaa6/0xe90 net/netlink/af_netlink.c:1929
sock_sendmsg_nosec net/socket.c:702 [inline]
sock_sendmsg net/socket.c:722 [inline]
____sys_sendmsg+0x5a2/0x900 net/socket.c:2385
___sys_sendmsg net/socket.c:2439 [inline]
__sys_sendmsg+0x319/0x400 net/socket.c:2468
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x43fa29
Code: 28 c3 e8 5a 14 00 00 66 2e 0f 1f 84 00 00 00 00 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcd5946088 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004004a0 RCX: 000000000043fa29
RDX: 0000000000000000 RSI: 0000000020000b40 RDI: 0000000000000003
RBP: 0000000000403490 R08: 0000000000000000 R09: 00000000004004a0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000403520
R13: 0000000000000000 R14: 00000000004ad018 R15: 00000000004004a0
Modules linked in:
---[ end trace d9ad06d2dab45e1b ]---
RIP: 0010:blk_mq_map_queue_type block/blk-mq.h:96 [inline]
RIP: 0010:blk_mq_get_sq_hctx block/blk-mq.c:1663 [inline]
RIP: 0010:blk_mq_run_hw_queues+0x14f/0x430 block/blk-mq.c:1682
Code: 80 3c 08 00 74 08 48 89 ef e8 0d 0f dd fd 44 89 fb 48 c1 e3 02 48 03 5d 00 48 89 d8 48 c1 e8 03 48 bd 00 00 00 00 00 fc ff df <8a> 04 28 84 c0 0f 85 b7 02 00 00 8b 03 49 8d 1c c4 48 89 d8 48 c1
RSP: 0018:ffffc9000183f160 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88801f912b38
RBP: dffffc0000000000 R08: ffffffff83eb6412 R09: ffffed1003f22687
R10: ffffed1003f22687 R11: 0000000000000000 R12: ffff88814615f4d8
R13: 0000000000000000 R14: ffff88801f912af0 R15: 0000000000000000
FS: 0000000001ab6300(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa915ace020 CR3: 0000000018231000 CR4: 00000000001506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Maybe it can be fixed like this as commit 6a03cd9843fa4dcf827dc3ad60fa9b4217f3057c did.

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 614d82e7fae4..d2548d36bf21 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -222,8 +222,8 @@ static void nbd_dev_remove(struct nbd_device *nbd)

        if (disk) {
                del_gendisk(disk);
-               blk_mq_free_tag_set(&nbd->tag_set);
                blk_cleanup_disk(disk);
+               blk_mq_free_tag_set(&nbd->tag_set);
        }

Also paride/pd.c needs the same change, is my understanding correct? Christoph.

Thanks,
Guoqing