On 3/9/20 1:49 PM, Dominik 'disconnect3d' Czarnota wrote:
> From: disconnect3d <dominik.b.czarnota@xxxxxxxxx>
>
> This patch fixes an off-by-one error in strncpy size argument in
> drivers/video/fbdev/nvidia/nvidia.c. The issue is that in:
>
> strncmp(this_opt, "noaccel", 6)
>
> the passed string literal: "noaccel" has 7 bytes (without the NULL byte)
> and the passed size argument is 6. As a result, the logic will also
> match/accept string "noacce" or "noacceX".
>
> This bug doesn't seem to have any security impact since its present in
> the driver's setup and just accepts slighty changed string to enable the
> `noaccel` flag.
>
> Signed-off-by: disconnect3d <dominik.b.czarnota@xxxxxxxxx>
Patch looks fine but please fix 'From:' and 'S-o-b:' lines,
per Documentation/process/submitting-patches.rst:
...
then you just add a line saying::
Signed-off-by: Random J Developer <random@xxxxxxxxxxxxxxxxxxxxx>
using your real name (sorry, no pseudonyms or anonymous contributions.)
...
Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics
> ---
>
> Notes:
> The bug could also be fixed by changing the size argument to
> `sizeof("string literal")-1` but I am not proposing this change as that
> would have to be changed in other places.
>
> There are also more cases like this in kernel sources which I
> reported/will report soon.
>
> This bug has been found by running a massive grep-like search using
> Google's BigQuery on GitHub repositories data. I am also going to work
> on a CodeQL/Semmle query to be able to find more sophisticated cases
> like this that can't be found via grepping.
>
> drivers/video/fbdev/nvidia/nvidia.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/video/fbdev/nvidia/nvidia.c b/drivers/video/fbdev/nvidia/nvidia.c
> index c583c018304d..b77efeb33477 100644
> --- a/drivers/video/fbdev/nvidia/nvidia.c
> +++ b/drivers/video/fbdev/nvidia/nvidia.c
> @@ -1470,7 +1470,7 @@ static int nvidiafb_setup(char *options)
> flatpanel = 1;
> } else if (!strncmp(this_opt, "hwcur", 5)) {
> hwcur = 1;
> - } else if (!strncmp(this_opt, "noaccel", 6)) {
> + } else if (!strncmp(this_opt, "noaccel", 7)) {
> noaccel = 1;
> } else if (!strncmp(this_opt, "noscale", 7)) {
> noscale = 1;
>
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