WSL2-Linux-Kernel/drivers/block
Jason Andryuk ffa12a3264 xen-blkfront: Handle NULL gendisk
[ Upstream commit f9710c357e ]

When a VBD is not fully created and then closed, the kernel can have a
NULL pointer dereference:

The reproducer is trivial:

[user@dom0 ~]$ sudo xl block-attach work backend=sys-usb vdev=xvdi target=/dev/sdz
[user@dom0 ~]$ xl block-list work
Vdev  BE  handle state evt-ch ring-ref BE-path
51712 0   241    4     -1     -1       /local/domain/0/backend/vbd/241/51712
51728 0   241    4     -1     -1       /local/domain/0/backend/vbd/241/51728
51744 0   241    4     -1     -1       /local/domain/0/backend/vbd/241/51744
51760 0   241    4     -1     -1       /local/domain/0/backend/vbd/241/51760
51840 3   241    3     -1     -1       /local/domain/3/backend/vbd/241/51840
                 ^ note state, the /dev/sdz doesn't exist in the backend

[user@dom0 ~]$ sudo xl block-detach work xvdi
[user@dom0 ~]$ xl block-list work
Vdev  BE  handle state evt-ch ring-ref BE-path
work is an invalid domain identifier

And its console has:

BUG: kernel NULL pointer dereference, address: 0000000000000050
PGD 80000000edebb067 P4D 80000000edebb067 PUD edec2067 PMD 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 1 PID: 52 Comm: xenwatch Not tainted 5.16.18-2.43.fc32.qubes.x86_64 #1
RIP: 0010:blk_mq_stop_hw_queues+0x5/0x40
Code: 00 48 83 e0 fd 83 c3 01 48 89 85 a8 00 00 00 41 39 5c 24 50 77 c0 5b 5d 41 5c 41 5d c3 c3 0f 1f 80 00 00 00 00 0f 1f 44 00 00 <8b> 47 50 85 c0 74 32 41 54 49 89 fc 55 53 31 db 49 8b 44 24 48 48
RSP: 0018:ffffc90000bcfe98 EFLAGS: 00010293
RAX: ffffffffc0008370 RBX: 0000000000000005 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000000
RBP: ffff88800775f000 R08: 0000000000000001 R09: ffff888006e620b8
R10: ffff888006e620b0 R11: f000000000000000 R12: ffff8880bff39000
R13: ffff8880bff39000 R14: 0000000000000000 R15: ffff88800604be00
FS:  0000000000000000(0000) GS:ffff8880f3300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000050 CR3: 00000000e932e002 CR4: 00000000003706e0
Call Trace:
 <TASK>
 blkback_changed+0x95/0x137 [xen_blkfront]
 ? read_reply+0x160/0x160
 xenwatch_thread+0xc0/0x1a0
 ? do_wait_intr_irq+0xa0/0xa0
 kthread+0x16b/0x190
 ? set_kthread_struct+0x40/0x40
 ret_from_fork+0x22/0x30
 </TASK>
Modules linked in: snd_seq_dummy snd_hrtimer snd_seq snd_seq_device snd_timer snd soundcore ipt_REJECT nf_reject_ipv4 xt_state xt_conntrack nft_counter nft_chain_nat xt_MASQUERADE nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nft_compat nf_tables nfnetlink intel_rapl_msr intel_rapl_common crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel xen_netfront pcspkr xen_scsiback target_core_mod xen_netback xen_privcmd xen_gntdev xen_gntalloc xen_blkback xen_evtchn ipmi_devintf ipmi_msghandler fuse bpf_preload ip_tables overlay xen_blkfront
CR2: 0000000000000050
---[ end trace 7bc9597fd06ae89d ]---
RIP: 0010:blk_mq_stop_hw_queues+0x5/0x40
Code: 00 48 83 e0 fd 83 c3 01 48 89 85 a8 00 00 00 41 39 5c 24 50 77 c0 5b 5d 41 5c 41 5d c3 c3 0f 1f 80 00 00 00 00 0f 1f 44 00 00 <8b> 47 50 85 c0 74 32 41 54 49 89 fc 55 53 31 db 49 8b 44 24 48 48
RSP: 0018:ffffc90000bcfe98 EFLAGS: 00010293
RAX: ffffffffc0008370 RBX: 0000000000000005 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000000
RBP: ffff88800775f000 R08: 0000000000000001 R09: ffff888006e620b8
R10: ffff888006e620b0 R11: f000000000000000 R12: ffff8880bff39000
R13: ffff8880bff39000 R14: 0000000000000000 R15: ffff88800604be00
FS:  0000000000000000(0000) GS:ffff8880f3300000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000050 CR3: 00000000e932e002 CR4: 00000000003706e0
Kernel panic - not syncing: Fatal exception
Kernel Offset: disabled

info->rq and info->gd are only set in blkfront_connect(), which is
called for state 4 (XenbusStateConnected).  Guard against using NULL
variables in blkfront_closing() to avoid the issue.

The rest of blkfront_closing looks okay.  If info->nr_rings is 0, then
for_each_rinfo won't do anything.

blkfront_remove also needs to check for non-NULL pointers before
cleaning up the gendisk and request queue.

Fixes: 05d69d950d "xen-blkfront: sanitize the removal state machine"
Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220601195341.28581-1-jandryuk@gmail.com
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-06-29 09:03:24 +02:00
..
aoe for-5.14/drivers-2021-06-29 2021-06-30 12:21:16 -07:00
drbd drbd: fix duplicate array initializer 2022-06-09 10:22:47 +02:00
mtip32xx block: fix surprise removal for drivers calling blk_set_queue_dying 2022-02-23 12:03:15 +01:00
null_blk null_blk: add error handling support for add_disk() 2021-08-23 12:55:46 -06:00
paride SCSI misc on 20210902 2021-09-02 15:09:46 -07:00
rnbd block/rnbd-clt-sysfs: fix a couple uninitialized variable bugs 2021-10-12 10:39:57 -06:00
rsxx for-5.14/drivers-2021-06-29 2021-06-30 12:21:16 -07:00
xen-blkback isystem: trim/fixup stdarg.h and other headers 2021-08-19 09:02:55 +09:00
zram zram: off by one in read_block_state() 2021-11-18 19:17:10 +01:00
Kconfig floppy: disable FDRAWCMD by default 2022-05-01 17:22:22 +02:00
Makefile drivers/block: remove the umem driver 2021-03-24 06:57:40 -06:00
amiflop.c block: drop unused includes in <linux/genhd.h> 2022-03-16 14:23:46 +01:00
ataflop.c block: drop unused includes in <linux/genhd.h> 2022-03-16 14:23:46 +01:00
brd.c brd: reduce the brd_devices_mutex scope 2021-10-17 06:51:19 -06:00
cryptoloop.c cryptoloop: add a deprecation warning 2021-08-27 10:44:54 -06:00
floppy.c floppy: use a statically allocated error counter 2022-05-25 09:57:21 +02:00
loop.c loop: use sysfs_emit() in the sysfs xxx show() 2022-04-08 14:23:55 +02:00
loop.h loop: reduce the loop_ctl_mutex scope 2021-09-03 22:14:40 -06:00
n64cart.c n64cart: convert bi_disk to bi_bdev->bd_disk fix build 2022-04-08 14:24:16 +02:00
nbd.c nbd: fix io hung while disconnecting device 2022-06-14 18:36:24 +02:00
pktcdvd.c block: move the bdi from the request_queue to the gendisk 2021-08-09 11:53:23 -06:00
ps3disk.c ps3disk: use memcpy_{from,to}_bvec 2021-08-02 13:37:27 -06:00
ps3vram.c ps3vram: use bvec_virt 2021-08-16 10:50:33 -06:00
rbd.c block: fix surprise removal for drivers calling blk_set_queue_dying 2022-02-23 12:03:15 +01:00
rbd_types.h libceph, rbd: replace zero-length array with flexible-array 2020-06-01 13:22:53 +02:00
sunvdc.c Char / Misc driver updates for 5.14-rc1 2021-07-05 13:42:16 -07:00
swim.c block: drop unused includes in <linux/genhd.h> 2022-03-16 14:23:46 +01:00
swim3.c swim3: use blk_mq_alloc_disk 2021-06-11 11:53:02 -06:00
swim_asm.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
sx8.c sx8: use the internal state machine to check if del_gendisk needs to be called 2021-08-12 10:29:36 -06:00
virtio_blk.c virtio_blk: fix the discard_granularity and discard_alignment queue limits 2022-06-09 10:22:53 +02:00
xen-blkfront.c xen-blkfront: Handle NULL gendisk 2022-06-29 09:03:24 +02:00
z2ram.c for-5.14/drivers-2021-06-29 2021-06-30 12:21:16 -07:00