scsi: sg: Do not sleep in atomic context

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: 97d27b0dd015 ("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>

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 4c62c597c7be93518a47c0832717d39ddd3811f8..b3af9b78fa123b5b4e0efa5c15fb674097b9db7f 100644 (file)
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -2208,9 +2208,17 @@ 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);