scsi: sg: Do not sleep in atomic context

commit 90449f2d1e1f020835cba5417234636937dd657e upstream.

sg_finish_rem_req() calls blk_rq_unmap_user(). The latter function may
sleep. Hence, call sg_finish_rem_req() with interrupts enabled instead
of disabled.

Reported-by: syzbot+c01f8e6e73f20459912e@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-scsi/691560c4.a70a0220.3124cb.001a.GAE@google.com/
Cc: Hannes Reinecke <hare@suse.de>
Cc: stable@vger.kernel.org
Fixes: 97d27b0 ("scsi: sg: close race condition in sg_remove_sfp_usercontext()")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://patch.msgid.link/20251113181643.1108973-1-bvanassche@acm.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ulrich Hecht <uli@kernel.org>

Author: bvanassche

drivers/scsi/sg.c

@@ -2219,9 +2219,17 @@ sg_remove_sfp_usercontext(struct work_struct *work)
 	write_lock_irqsave(&sfp->rq_list_lock, iflags);
 	while (!list_empty(&sfp->rq_list)) {
 		srp = list_first_entry(&sfp->rq_list, Sg_request, entry);
-		sg_finish_rem_req(srp);
 		list_del(&srp->entry);
+		write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+
+		sg_finish_rem_req(srp);
+		/*
+		 * sg_rq_end_io() uses srp->parentfp. Hence, only clear
+		 * srp->parentfp after blk_mq_free_request() has been called.
+		 */
 		srp->parentfp = NULL;
+
+		write_lock_irqsave(&sfp->rq_list_lock, iflags);
 	}
 	write_unlock_irqrestore(&sfp->rq_list_lock, iflags);