On 5/27/19 7:22 AM, YueHaibing wrote:
> If alloc_workqueue fails in alua_init, it should return
> -ENOMEM, otherwise it will trigger null-ptr-deref while
> unloading module which calls destroy_workqueue dereference
> wq->lock like this:
>
> BUG: KASAN: null-ptr-deref in __lock_acquire+0x6b4/0x1ee0
> Read of size 8 at addr 0000000000000080 by task syz-executor.0/7045
>
> CPU: 0 PID: 7045 Comm: syz-executor.0 Tainted: G C 5.1.0+ #28
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1
> Call Trace:
> dump_stack+0xa9/0x10e
> __kasan_report+0x171/0x18d
> ? __lock_acquire+0x6b4/0x1ee0
> kasan_report+0xe/0x20
> __lock_acquire+0x6b4/0x1ee0
> lock_acquire+0xb4/0x1b0
> __mutex_lock+0xd8/0xb90
> drain_workqueue+0x25/0x290
> destroy_workqueue+0x1f/0x3f0
> __x64_sys_delete_module+0x244/0x330
> do_syscall_64+0x72/0x2a0
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
> Fixes: 03197b61c5ec ("scsi_dh_alua: Use workqueue for RTPG")
> Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
> ---
> drivers/scsi/device_handler/scsi_dh_alua.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
> index d7ac498ba35a..2a9dcb8973b7 100644
> --- a/drivers/scsi/device_handler/scsi_dh_alua.c
> +++ b/drivers/scsi/device_handler/scsi_dh_alua.c
> @@ -1174,10 +1174,8 @@ static int __init alua_init(void)
> int r;
>
> kaluad_wq = alloc_workqueue("kaluad", WQ_MEM_RECLAIM, 0);
> - if (!kaluad_wq) {
> - /* Temporary failure, bypass */
> - return SCSI_DH_DEV_TEMP_BUSY;
> - }
> + if (!kaluad_wq)
> + return -ENOMEM;
>
> r = scsi_register_device_handler(&alua_dh);
> if (r != 0) {
>
Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
