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Subject[RFC PATCH] RDMA/srp: Fix use-after-free in srp_exit_cmd_priv
Date
srp_exit_cmd_priv() will try to access srp_device by Scsi_Host like below:

Scsi_Host srp_target_port srp_host srp_device
+------------------+ +-- +--------------+ +>+----------+ +->+---------+
| | | | | | | | | | |
| | | | *srp_host +--+ | *srp_dev +---+ | *dev |
+-+hostdata--------+-+ | | | | | |
| | srp_target_port| | | | | | |
| | | | | | | | |
| | | | | | | | |
+-+----------------+---- +--------------+ +----------+ +---------+

But sometims Scsi_Host still keeps the reference to srp_host that is
possible released already. This could be happend if i frequently abort
(Ctrl-c) the blktests during it was running and then cause below error:

[ 952.294952] scsi 9:0:0:1: alua: Detached
[ 952.298232] ==================================================================
[ 952.298235] BUG: KASAN: use-after-free in srp_exit_cmd_priv+0x27/0xd0 [ib_srp]
[ 952.298254] Read of size 8 at addr ffff888100337000 by task multipathd/16727
[ 952.298258]
[ 952.298263] CPU: 0 PID: 16727 Comm: multipathd Not tainted 5.19.0-rc1-roce-flush+ #78
[ 952.298268] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-27-g64f37cc530f1-prebuilt.qemu.org 04/01/2014
[ 952.298272] Call Trace:
[ 952.298281] <TASK>
[ 952.298283] dump_stack_lvl+0x34/0x44
[ 952.298303] print_report.cold+0x5e/0x5db
[ 952.298317] ? schedule_timeout+0x1c4/0x210
[ 952.298329] ? srp_exit_cmd_priv+0x27/0xd0 [ib_srp]
[ 952.298343] kasan_report+0xab/0x120
[ 952.298356] ? srp_exit_cmd_priv+0x27/0xd0 [ib_srp]
[ 952.298370] srp_exit_cmd_priv+0x27/0xd0 [ib_srp]
[ 952.298384] scsi_mq_exit_request+0x4d/0x70
[ 952.298394] blk_mq_free_rqs+0x143/0x410
[ 952.298406] __blk_mq_free_map_and_rqs+0x6e/0x100
[ 952.298413] blk_mq_free_tag_set+0x2b/0x160
[ 952.298419] scsi_host_dev_release+0xf3/0x1a0
[ 952.298427] device_release+0x54/0xe0
[ 952.298438] kobject_put+0xa5/0x120
[ 952.298451] device_release+0x54/0xe0
[ 952.298456] kobject_put+0xa5/0x120
[ 952.298461] scsi_device_dev_release_usercontext+0x4c1/0x4e0
[ 952.298468] ? scsi_device_cls_release+0x10/0x10
[ 952.298474] execute_in_process_context+0x23/0x90
[ 952.298483] device_release+0x54/0xe0
[ 952.298487] kobject_put+0xa5/0x120
[ 952.298493] scsi_disk_release+0x3f/0x50
[ 952.298500] device_release+0x54/0xe0
[ 952.298504] kobject_put+0xa5/0x120
[ 952.298509] disk_release+0x17f/0x1b0
[ 952.298516] device_release+0x54/0xe0
[ 952.298520] kobject_put+0xa5/0x120
[ 952.298526] dm_put_table_device+0xa3/0x160 [dm_mod]
[ 952.298559] dm_put_device+0xd0/0x140 [dm_mod]
[ 952.298592] free_priority_group+0xd8/0x110 [dm_multipath]
[ 952.298602] free_multipath+0x94/0xe0 [dm_multipath]
[ 952.298612] dm_table_destroy+0xa2/0x1e0 [dm_mod]
[ 952.298645] __dm_destroy+0x196/0x350 [dm_mod]
[ 952.298676] dev_remove+0x10c/0x160 [dm_mod]
[ 952.298709] ctl_ioctl+0x2c2/0x590 [dm_mod]
[ 952.298751] ? table_clear+0x100/0x100 [dm_mod]
[ 952.298784] ? remove_all+0x40/0x40 [dm_mod]
[ 952.298820] ? __blkcg_punt_bio_submit+0xd0/0xd0
[ 952.298828] ? __rcu_read_unlock+0x43/0x60
[ 952.298838] dm_ctl_ioctl+0x5/0x10 [dm_mod]
[ 952.298870] __x64_sys_ioctl+0xb4/0xf0
[ 952.298784] ? remove_all+0x40/0x40 [dm_mod]
[ 952.298820] ? __blkcg_punt_bio_submit+0xd0/0xd0
[ 952.298828] ? __rcu_read_unlock+0x43/0x60
[ 952.298838] dm_ctl_ioctl+0x5/0x10 [dm_mod]
[ 952.298870] __x64_sys_ioctl+0xb4/0xf0
[ 952.298877] do_syscall_64+0x3b/0x90
[ 952.298884] entry_SYSCALL_64_after_hwframe+0x46/0xb0
[ 952.298890] RIP: 0033:0x7f1d7f4654eb
[ 952.298896] Code: ff ff ff 85 c0 79 9b 49 c7 c4 ff ff ff ff 5b 5d 4c 89 e0 41 5c c3 66 0f 1f 84 00 00 00 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 55 b9 0c 00 f7 d8 64 89 01 48
[ 952.298903] RSP: 002b:00007f1d7de21558 EFLAGS: 00000206 ORIG_RAX: 0000000000000010
[ 952.298912] RAX: ffffffffffffffda RBX: 00007f1d7f682050 RCX: 00007f1d7f4654eb
[ 952.298916] RDX: 00007f1d6c016730 RSI: 00000000c138fd04 RDI: 0000000000000005
[ 952.298919] RBP: 00007f1d7f6be2b6 R08: 00007f1d7de1f2b0 R09: 00007f1d7de1f200
[ 952.298922] R10: 0000000000000001 R11: 0000000000000206 R12: 00007f1d6c001100
[ 952.298925] R13: 00007f1d6c016760 R14: 00007f1d6c0167e0 R15: 00007f1d6c016730
[ 952.298930] </TASK>
[ 952.298933]
[ 952.298934] Allocated by task 16887:
[ 952.298939] kasan_save_stack+0x1e/0x40
[ 952.298944] __kasan_kmalloc+0x81/0xa0
[ 952.298948] srp_add_one+0x32a/0x540 [ib_srp]
[ 952.298961] add_client_context+0x23b/0x300 [ib_core]
[ 952.299043] ib_register_client+0x1d5/0x220 [ib_core]
[ 952.299123] 0xffffffffc0a60149
[ 952.299125] do_one_initcall+0x84/0x280
[ 952.299132] do_init_module+0xdf/0x2e0
[ 952.299136] load_module+0x2b9e/0x2c90
[ 952.299139] __do_sys_finit_module+0x111/0x190
[ 952.299143] do_syscall_64+0x3b/0x90
[ 952.299147] entry_SYSCALL_64_after_hwframe+0x46/0xb0
[ 952.299152]
[ 952.299153] Freed by task 17289:
[ 952.299156] kasan_save_stack+0x1e/0x40
[ 952.299160] kasan_set_track+0x21/0x30
[ 952.299164] kasan_set_free_info+0x20/0x30
[ 952.299169] __kasan_slab_free+0x108/0x170
[ 952.299173] kfree+0x9a/0x320
[ 952.299177] srp_remove_one+0x114/0x180 [ib_srp]
[ 952.299189] remove_client_context+0x8f/0xd0 [ib_core]
[ 952.299269] disable_device+0xee/0x1e0 [ib_core]
[ 952.299348] __ib_unregister_device+0x59/0xf0 [ib_core]
[ 952.299429] ib_unregister_device_and_put+0x3b/0x50 [ib_core]
[ 952.299509] nldev_dellink+0x126/0x1b0 [ib_core]
[ 952.299592] rdma_nl_rcv_msg+0x1cc/0x310 [ib_core]
[ 952.299673] rdma_nl_rcv+0x172/0x200 [ib_core]
[ 952.299760] netlink_unicast+0x36b/0x4a0
[ 952.299770] netlink_sendmsg+0x3a9/0x6d0
[ 952.299774] sock_sendmsg+0x91/0xa0
[ 952.299783] __sys_sendto+0x16f/0x210
[ 952.299788] __x64_sys_sendto+0x6f/0x80
[ 952.299792] do_syscall_64+0x3b/0x90
[ 952.299795] entry_SYSCALL_64_after_hwframe+0x46/0xb0
[ 952.299801]
[ 952.299801] Last potentially related work creation:
[ 952.299803] kasan_save_stack+0x1e/0x40
[ 952.299807] __kasan_record_aux_stack+0x97/0xa0
[ 952.299812] call_rcu+0x41/0x580
[ 952.299816] rht_deferred_worker+0x552/0x700
[ 952.299830] kthread+0x167/0x1a0
[ 952.299835] ret_from_fork+0x22/0x30
[ 952.299839]
[ 952.299840] The buggy address belongs to the object at ffff888100337000
[ 952.299840] which belongs to the cache kmalloc-1k of size 1024
[ 952.299844] The buggy address is located 0 bytes inside of
[ 952.299844] 1024-byte region [ffff888100337000, ffff888100337400)
[ 952.299848]
[ 952.299849] The buggy address belongs to the physical page:
[ 952.299850] page:000000005d3ee749 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x100334
[ 952.299857] head:000000005d3ee749 order:2 compound_mapcount:0 compound_pincount:0
[ 952.299860] flags: 0x100000000010200(slab|head|node=0|zone=2)
[ 952.299868] raw: 0100000000010200 0000000000000000 dead000000000001 ffff888100041dc0
[ 952.299872] raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000
[ 952.299874] page dumped because: kasan: bad access detected
[ 952.299876]
[ 952.299876] Memory state around the buggy address:
[ 952.299878] ffff888100336f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 952.299882] ffff888100336f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[ 952.299885] >ffff888100337000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 952.299887] ^
[ 952.299889] ffff888100337080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
[ 952.299892] ffff888100337100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
---
This patch is mainly to report the use-after-free bug. It seems the proposal
increasing the IB device's reference count is a bit ugly. Feedbacks and
ideas are very welcome.
---
drivers/infiniband/ulp/srp/ib_srp.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 6058abf42ba7..5981a0ea7a19 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -979,6 +979,8 @@ static int srp_exit_cmd_priv(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
DMA_TO_DEVICE);
}
kfree(req->indirect_desc);
+ /* pair with get_device() in srp_init_cmd_priv() */
+ put_device(&ibdev->dev);

return 0;
}
@@ -1006,12 +1008,14 @@ static int srp_init_cmd_priv(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
target->indirect_size,
DMA_TO_DEVICE);
if (ib_dma_mapping_error(ibdev, dma_addr)) {
+ get_device(&ibdev->dev);
srp_exit_cmd_priv(shost, cmd);
goto out;
}

req->indirect_dma_addr = dma_addr;
ret = 0;
+ get_device(&ibdev->dev);

out:
return ret;
--
2.31.1


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