[PATCH] drm: etnaviv: fix strncpy sizeof argument

[PATCH] drm: etnaviv: fix strncpy sizeof argument

[Bo YU]

Calling strncpy with a maximum size argument of 64 bytes on destination
array "domain->name" of size 64 bytes might leave the destination string
unterminated.

Detected by CoverityScan, CID# 1443992:  Memory - illegal accesses
(BUFFER_SIZE_WARNING)

Fixes: 9e2c2e2730126 (drm/etnaviv: add infrastructure to query perf counter)
Signed-off-by: Bo YU <tsu.yubo@gmail.com>
---
 drivers/gpu/drm/etnaviv/etnaviv_perfmon.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c b/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c
index 4227a4006c34..08ca3c44be48 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c
@@ -414,7 +414,7 @@ int etnaviv_pm_query_dom(struct etnaviv_gpu *gpu,
 
 	domain->id = domain->iter;
 	domain->nr_signals = dom->nr_signals;
-	strncpy(domain->name, dom->name, sizeof(domain->name));
+	strncpy(domain->name, dom->name, sizeof(dom->name));
 
 	domain->iter++;
 	if (domain->iter == meta->nr_domains)
-- 
2.11.0

Re: [PATCH] drm: etnaviv: fix strncpy sizeof argument

[Russell King - ARM Linux admin]

On Mon, Mar 18, 2019 at 10:57:55PM -0400, Bo YU wrote:
> Calling strncpy with a maximum size argument of 64 bytes on destination
> array "domain->name" of size 64 bytes might leave the destination string
> unterminated.
> 
> Detected by CoverityScan, CID# 1443992:  Memory - illegal accesses
> (BUFFER_SIZE_WARNING)
> 
> Fixes: 9e2c2e2730126 (drm/etnaviv: add infrastructure to query perf counter)
> Signed-off-by: Bo YU <tsu.yubo@gmail.com>
> ---
>  drivers/gpu/drm/etnaviv/etnaviv_perfmon.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c b/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c
> index 4227a4006c34..08ca3c44be48 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c
> @@ -414,7 +414,7 @@ int etnaviv_pm_query_dom(struct etnaviv_gpu *gpu,
>  
>  	domain->id = domain->iter;
>  	domain->nr_signals = dom->nr_signals;
> -	strncpy(domain->name, dom->name, sizeof(domain->name));
> +	strncpy(domain->name, dom->name, sizeof(dom->name));

This introduces an overflow bug if sizeof(dom->name) >
sizeof(domain->name).  If both sizes are the same, then there is no
effect.

strlcpy() would be a better replacement, it guarantees that the
destination will be correctly terminated.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
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Re: [PATCH] drm: etnaviv: fix strncpy sizeof argument

[Bo YU]

On Tue, Mar 19, 2019 at 6:22 PM Russell King - ARM Linux admin
<linux@armlinux.org.uk> wrote:
>
> On Mon, Mar 18, 2019 at 10:57:55PM -0400, Bo YU wrote:
> > Calling strncpy with a maximum size argument of 64 bytes on destination
> > array "domain->name" of size 64 bytes might leave the destination string
> > unterminated.
> >
> > Detected by CoverityScan, CID# 1443992:  Memory - illegal accesses
> > (BUFFER_SIZE_WARNING)
> >
> > Fixes: 9e2c2e2730126 (drm/etnaviv: add infrastructure to query perf counter)
> > Signed-off-by: Bo YU <tsu.yubo@gmail.com>
> > ---
> >  drivers/gpu/drm/etnaviv/etnaviv_perfmon.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c b/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c
> > index 4227a4006c34..08ca3c44be48 100644
> > --- a/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c
> > +++ b/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c
> > @@ -414,7 +414,7 @@ int etnaviv_pm_query_dom(struct etnaviv_gpu *gpu,
> >
> >       domain->id = domain->iter;
> >       domain->nr_signals = dom->nr_signals;
> > -     strncpy(domain->name, dom->name, sizeof(domain->name));
> > +     strncpy(domain->name, dom->name, sizeof(dom->name));
>
> This introduces an overflow bug if sizeof(dom->name) >
> sizeof(domain->name).  If both sizes are the same, then there is no
> effect.
Oops,It seems more worse than original code.
>
> strlcpy() would be a better replacement, it guarantees that the
> destination will be correctly terminated.
But there are too many strcpy like usage in kernel, Does it matter?
>
> --
> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
> FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
> According to speedtest.net: 11.9Mbps down 500kbps up