2020-12-07 14:57:11

by Colin King

Subject: [PATCH][next] block/rnbd: fix a null pointer dereference on dev->blk_symlink_name

From: Colin Ian King <[email protected]>

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 <[email protected]>
---
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

2020-12-07 15:06:46

by Jinpu Wang

Subject: Re: [PATCH][next] block/rnbd: fix a null pointer dereference on dev->blk_symlink_name

On Mon, Dec 7, 2020 at 4:01 PM Jens Axboe <[email protected]> wrote:
>
> On 12/7/20 7:54 AM, Colin King wrote:
> > From: Colin Ian King <[email protected]>
> >
> > 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).
>
> Applied, thanks.

Thanks Colin for the fix, and thanks Jens for taking care of this.

Jack Wang

2020-12-07 15:07:07

by Jens Axboe

Subject: Re: [PATCH][next] block/rnbd: fix a null pointer dereference on dev->blk_symlink_name

On 12/7/20 7:54 AM, Colin King wrote:
> From: Colin Ian King <[email protected]>
>
> 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).

Applied, thanks.

--
Jens Axboe