linux-kernel - [PATCH][next] scsi: sg: Fix use of pointer sfp after it has been kfree'd

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Date:   Thu, 11 Mar 2021 10:37:17 +0000
From:   Colin King <colin.king@...onical.com>
To:     Doug Gilbert <dgilbert@...erlog.com>,
        "James E . J . Bottomley" <jejb@...ux.ibm.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        Hannes Reinecke <hare@...e.de>, linux-scsi@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH][next] scsi: sg: Fix use of pointer sfp after it has been kfree'd

From: Colin Ian King <colin.king@...onical.com>

Currently SG_LOG is referencing sfp after it has been kfree'd which
is probably a bad thing to do. Fix this by kfree'ing sfp after
SG_LOG.

Addresses-Coverity: ("Use after free")
Fixes: af1fc95db445 ("scsi: sg: Replace rq array with xarray")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/scsi/sg.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 2d4bbc1a1727..79f05afa4407 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -3799,10 +3799,10 @@ sg_add_sfp(struct sg_device *sdp)
 	if (rbuf_len > 0) {
 		srp = sg_build_reserve(sfp, rbuf_len);
 		if (IS_ERR(srp)) {
-			kfree(sfp);
 			err = PTR_ERR(srp);
 			SG_LOG(1, sfp, "%s: build reserve err=%ld\n", __func__,
 			       -err);
+			kfree(sfp);
 			return ERR_PTR(err);
 		}
 		if (srp->sgat_h.buflen < rbuf_len) {
-- 
2.30.2