[PATCH AUTOSEL 5.6 17/68] null_blk: Fix the null_add_dev() error path

Sasha Levin
2020-04-10T04:02:55Z

From: Bart Van Assche <bvanassche@acm.org>

[ Upstream commit 2004bfdef945fe55196db6b9cdf321fbc75bb0de ]

If null_add_dev() fails, clear dev->nullb.

This patch fixes the following KASAN complaint:

BUG: KASAN: use-after-free in nullb_device_submit_queues_store+0xcf/0x160 [null_blk]
Read of size 8 at addr ffff88803280fc30 by task check/8409

Call Trace:
dump_stack+0xa5/0xe6
print_address_description.constprop.0+0x26/0x260
__kasan_report.cold+0x7b/0x99
kasan_report+0x16/0x20
__asan_load8+0x58/0x90
nullb_device_submit_queues_store+0xcf/0x160 [null_blk]
configfs_write_file+0x1c4/0x250 [configfs]
__vfs_write+0x4c/0x90
vfs_write+0x145/0x2c0
ksys_write+0xd7/0x180
__x64_sys_write+0x47/0x50
do_syscall_64+0x6f/0x2f0
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7ff370926317
Code: 64 89 02 48 c7 c0 ff ff ff ff eb bb 0f 1f 80 00 00 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24
RSP: 002b:00007fff2dd2da48 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007ff370926317
RDX: 0000000000000002 RSI: 0000559437ef23f0 RDI: 0000000000000001
RBP: 0000559437ef23f0 R08: 000000000000000a R09: 0000000000000001
R10: 0000559436703471 R11: 0000000000000246 R12: 0000000000000002
R13: 00007ff370a006a0 R14: 00007ff370a014a0 R15: 00007ff370a008a0

Allocated by task 8409:
save_stack+0x23/0x90
__kasan_kmalloc.constprop.0+0xcf/0xe0
kasan_kmalloc+0xd/0x10
kmem_cache_alloc_node_trace+0x129/0x4c0
null_add_dev+0x24a/0xe90 [null_blk]
nullb_device_power_store+0x1b6/0x270 [null_blk]
configfs_write_file+0x1c4/0x250 [configfs]
__vfs_write+0x4c/0x90
vfs_write+0x145/0x2c0
ksys_write+0xd7/0x180
__x64_sys_write+0x47/0x50
do_syscall_64+0x6f/0x2f0
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 8409:
save_stack+0x23/0x90
__kasan_slab_free+0x112/0x160
kasan_slab_free+0x12/0x20
kfree+0xdf/0x250
null_add_dev+0xaf3/0xe90 [null_blk]
nullb_device_power_store+0x1b6/0x270 [null_blk]
configfs_write_file+0x1c4/0x250 [configfs]
__vfs_write+0x4c/0x90
vfs_write+0x145/0x2c0
ksys_write+0xd7/0x180
__x64_sys_write+0x47/0x50
do_syscall_64+0x6f/0x2f0
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Fixes: 2984c8684f96 ("nullb: factor disk parameters")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Cc: Johannes Thumshirn <jth@kernel.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/block/null_blk_main.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
index 133060431dbdb..8ada43b3eca13 100644
--- a/drivers/block/null_blk_main.c
+++ b/drivers/block/null_blk_main.c
@@ -1788,6 +1788,7 @@ static int null_add_dev(struct nullb_device *dev)
cleanup_queues(nullb);
out_free_nullb:
kfree(nullb);
+ dev->nullb = NULL;
out:
return rv;
}
--
2.20.1