From: YueHaibing Date: Mon, 27 May 2019 22:22:09 +0800 Subject: scsi: scsi_dh_alua: Fix possible null-ptr-deref Git-commit: 12e750bc62044de096ab9a95201213fd912b9994 Patch-mainline: v5.2-rc3 References: git-fixes 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 Fixes: 03197b61c5ec ("scsi_dh_alua: Use workqueue for RTPG") Signed-off-by: YueHaibing Reviewed-by: Bart Van Assche Signed-off-by: Martin K. Petersen Acked-by: Lee Duncan --- 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) {