[PATCH AUTOSEL for 4.4 026/167] scsi: sg: don't return bogus Sg_requests

From: Sasha Levin
Date: Mon Mar 19 2018 - 13:31:30 EST


From: Johannes Thumshirn <jthumshirn@xxxxxxx>

[ Upstream commit 48ae8484e9fc324b4968d33c585e54bc98e44d61 ]

If the list search in sg_get_rq_mark() fails to find a valid request, we
return a bogus element. This then can later lead to a GPF in
sg_remove_scat().

So don't return bogus Sg_requests in sg_get_rq_mark() but NULL in case
the list search doesn't find a valid request.

Signed-off-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
Reported-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Doug Gilbert <dgilbert@xxxxxxxxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
Acked-by: Doug Gilbert <dgilbert@xxxxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
drivers/scsi/sg.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 0f0ff75755e0..4ce6a09002ad 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -2072,11 +2072,12 @@ sg_get_rq_mark(Sg_fd * sfp, int pack_id)
if ((1 == resp->done) && (!resp->sg_io_owned) &&
((-1 == pack_id) || (resp->header.pack_id == pack_id))) {
resp->done = 2; /* guard against other readers */
- break;
+ write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
+ return resp;
}
}
write_unlock_irqrestore(&sfp->rq_list_lock, iflags);
- return resp;
+ return NULL;
}

/* always adds to end of list */
--
2.14.1