linux-kernel - [PATCH][next] block/rnbd: fix a null pointer dereference on dev->blk_symlink

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Message-Id: <20201207145446.169978-1-colin.king@canonical.com>
Date:   Mon,  7 Dec 2020 14:54:46 +0000
From:   Colin King <colin.king@...onical.com>
To:     Danil Kipnis <danil.kipnis@...ud.ionos.com>,
        Jack Wang <jinpu.wang@...ud.ionos.com>,
        Jens Axboe <axboe@...nel.dk>, Jason Gunthorpe <jgg@...pe.ca>,
        Bart Van Assche <bvanassche@....org>,
        linux-block@...r.kernel.org
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH][next] block/rnbd: fix a null pointer dereference on dev->blk_symlink_name

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

Currently in the case where dev->blk_symlink_name fails to be allocates
the error return path attempts to set an end-of-string character to
the unallocated dev->blk_symlink_name causing a null pointer dereference
error. Fix this by returning with an explicity ENOMEM error (which also
is missing in the original code as was not initialized).

Addresses-Coverity: ("Dereference after null check")
Fixes: 1eb54f8f5dd8 ("block/rnbd: client: sysfs interface functions")
Signed-off-by: Colin Ian King <colin.king@...onical.com>
---
 drivers/block/rnbd/rnbd-clt-sysfs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/rnbd/rnbd-clt-sysfs.c b/drivers/block/rnbd/rnbd-clt-sysfs.c
index c3c96a567568..a7caeedeb198 100644
--- a/drivers/block/rnbd/rnbd-clt-sysfs.c
+++ b/drivers/block/rnbd/rnbd-clt-sysfs.c
@@ -499,7 +499,7 @@ static int rnbd_clt_add_dev_symlink(struct rnbd_clt_dev *dev)
 	dev->blk_symlink_name = kzalloc(len, GFP_KERNEL);
 	if (!dev->blk_symlink_name) {
 		rnbd_clt_err(dev, "Failed to allocate memory for blk_symlink_name\n");
-		goto out_err;
+		return -ENOMEM;
 	}
 
 	ret = rnbd_clt_get_path_name(dev, dev->blk_symlink_name,
-- 
2.29.2