diff options
| author | Zheng Qixing <zhengqixing@huawei.com> | 2025-06-12 21:24:05 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-07-17 18:37:17 +0200 |
| commit | 8586552df591e0a367eff44af0c586213eeecc3f (patch) | |
| tree | c4295f6cca8eaec298d4d4b7115cec89550df2a4 | |
| parent | 1bbdf4213711bb6dc365e7628430a63dd3280794 (diff) | |
nbd: fix uaf in nbd_genl_connect() error path
[ Upstream commit aa9552438ebf015fc5f9f890dbfe39f0c53cf37e ]
There is a use-after-free issue in nbd:
block nbd6: Receive control failed (result -104)
block nbd6: shutting down sockets
==================================================================
BUG: KASAN: slab-use-after-free in recv_work+0x694/0xa80 drivers/block/nbd.c:1022
Write of size 4 at addr ffff8880295de478 by task kworker/u33:0/67
CPU: 2 UID: 0 PID: 67 Comm: kworker/u33:0 Not tainted 6.15.0-rc5-syzkaller-00123-g2c89c1b655c0 #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: nbd6-recv recv_work
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:408 [inline]
print_report+0xc3/0x670 mm/kasan/report.c:521
kasan_report+0xe0/0x110 mm/kasan/report.c:634
check_region_inline mm/kasan/generic.c:183 [inline]
kasan_check_range+0xef/0x1a0 mm/kasan/generic.c:189
instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
atomic_dec include/linux/atomic/atomic-instrumented.h:592 [inline]
recv_work+0x694/0xa80 drivers/block/nbd.c:1022
process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
process_scheduled_works kernel/workqueue.c:3319 [inline]
worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
kthread+0x3c2/0x780 kernel/kthread.c:464
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:153
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
nbd_genl_connect() does not properly stop the device on certain
error paths after nbd_start_device() has been called. This causes
the error path to put nbd->config while recv_work continue to use
the config after putting it, leading to use-after-free in recv_work.
This patch moves nbd_start_device() after the backend file creation.
Reported-by: syzbot+48240bab47e705c53126@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/68227a04.050a0220.f2294.00b5.GAE@google.com/T/
Fixes: 6497ef8df568 ("nbd: provide a way for userspace processes to identify device backends")
Signed-off-by: Zheng Qixing <zhengqixing@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20250612132405.364904-1-zhengqixing@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | drivers/block/nbd.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 450458267e6e..c705acc4d6f4 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -2136,9 +2136,7 @@ again: goto out; } } - ret = nbd_start_device(nbd); - if (ret) - goto out; + if (info->attrs[NBD_ATTR_BACKEND_IDENTIFIER]) { nbd->backend = nla_strdup(info->attrs[NBD_ATTR_BACKEND_IDENTIFIER], GFP_KERNEL); @@ -2154,6 +2152,8 @@ again: goto out; } set_bit(NBD_RT_HAS_BACKEND_FILE, &config->runtime_flags); + + ret = nbd_start_device(nbd); out: mutex_unlock(&nbd->config_lock); if (!ret) { |