* [PATCH] drm/mm: avoid possible null pointer dereference @ 2016-05-18 20:17 Heinrich Schuchardt 2016-05-23 10:27 ` Eric Engestrom 0 siblings, 1 reply; 8+ messages in thread From: Heinrich Schuchardt @ 2016-05-18 20:17 UTC (permalink / raw) To: David Airlie; +Cc: dri-devel, linux-kernel, Heinrich Schuchardt Do not dereference node before the check if node is NULL. Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de> --- drivers/gpu/drm/drm_mm.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c index 04de6fd..cb39f45 100644 --- a/drivers/gpu/drm/drm_mm.c +++ b/drivers/gpu/drm/drm_mm.c @@ -179,12 +179,14 @@ static void drm_mm_insert_helper(struct drm_mm_node *hole_node, int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node) { struct drm_mm_node *hole; - u64 end = node->start + node->size; + u64 end; u64 hole_start; u64 hole_end; BUG_ON(node == NULL); + end = node->start + node->size; + /* Find the relevant hole to add our node to */ drm_mm_for_each_hole(hole, mm, hole_start, hole_end) { if (hole_start > node->start || hole_end < end) -- 2.1.4 ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH] drm/mm: avoid possible null pointer dereference 2016-05-18 20:17 [PATCH] drm/mm: avoid possible null pointer dereference Heinrich Schuchardt @ 2016-05-23 10:27 ` Eric Engestrom 2016-05-23 12:56 ` Daniel Vetter 0 siblings, 1 reply; 8+ messages in thread From: Eric Engestrom @ 2016-05-23 10:27 UTC (permalink / raw) To: Heinrich Schuchardt; +Cc: David Airlie, linux-kernel, dri-devel On Wed, May 18, 2016 at 10:17:19PM +0200, Heinrich Schuchardt wrote: > Do not dereference node before the check if node is NULL. > > Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de> > --- > drivers/gpu/drm/drm_mm.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c > index 04de6fd..cb39f45 100644 > --- a/drivers/gpu/drm/drm_mm.c > +++ b/drivers/gpu/drm/drm_mm.c > @@ -179,12 +179,14 @@ static void drm_mm_insert_helper(struct drm_mm_node *hole_node, > int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node) > { > struct drm_mm_node *hole; > - u64 end = node->start + node->size; > + u64 end; > u64 hole_start; > u64 hole_end; > > BUG_ON(node == NULL); > > + end = node->start + node->size; > + > /* Find the relevant hole to add our node to */ > drm_mm_for_each_hole(hole, mm, hole_start, hole_end) { > if (hole_start > node->start || hole_end < end) > -- > 2.1.4 Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com> ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] drm/mm: avoid possible null pointer dereference 2016-05-23 10:27 ` Eric Engestrom @ 2016-05-23 12:56 ` Daniel Vetter 2016-05-23 13:02 ` Chris Wilson 0 siblings, 1 reply; 8+ messages in thread From: Daniel Vetter @ 2016-05-23 12:56 UTC (permalink / raw) To: Eric Engestrom; +Cc: Heinrich Schuchardt, linux-kernel, dri-devel On Mon, May 23, 2016 at 11:27:14AM +0100, Eric Engestrom wrote: > On Wed, May 18, 2016 at 10:17:19PM +0200, Heinrich Schuchardt wrote: > > Do not dereference node before the check if node is NULL. > > > > Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de> > > --- > > drivers/gpu/drm/drm_mm.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c > > index 04de6fd..cb39f45 100644 > > --- a/drivers/gpu/drm/drm_mm.c > > +++ b/drivers/gpu/drm/drm_mm.c > > @@ -179,12 +179,14 @@ static void drm_mm_insert_helper(struct drm_mm_node *hole_node, > > int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node) > > { > > struct drm_mm_node *hole; > > - u64 end = node->start + node->size; > > + u64 end; > > u64 hole_start; > > u64 hole_end; > > > > BUG_ON(node == NULL); > > > > + end = node->start + node->size; > > + > > /* Find the relevant hole to add our node to */ > > drm_mm_for_each_hole(hole, mm, hole_start, hole_end) { > > if (hole_start > node->start || hole_end < end) > > -- > > 2.1.4 > > Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com> Applied to drm-misc, thanks. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] drm/mm: avoid possible null pointer dereference 2016-05-23 12:56 ` Daniel Vetter @ 2016-05-23 13:02 ` Chris Wilson 2016-05-23 13:38 ` Eric Engestrom 0 siblings, 1 reply; 8+ messages in thread From: Chris Wilson @ 2016-05-23 13:02 UTC (permalink / raw) To: Eric Engestrom, Heinrich Schuchardt, linux-kernel, dri-devel On Mon, May 23, 2016 at 02:56:45PM +0200, Daniel Vetter wrote: > On Mon, May 23, 2016 at 11:27:14AM +0100, Eric Engestrom wrote: > > On Wed, May 18, 2016 at 10:17:19PM +0200, Heinrich Schuchardt wrote: > > > Do not dereference node before the check if node is NULL. > > > > > > Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de> > > > --- > > > drivers/gpu/drm/drm_mm.c | 4 +++- > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c > > > index 04de6fd..cb39f45 100644 > > > --- a/drivers/gpu/drm/drm_mm.c > > > +++ b/drivers/gpu/drm/drm_mm.c > > > @@ -179,12 +179,14 @@ static void drm_mm_insert_helper(struct drm_mm_node *hole_node, > > > int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node) > > > { > > > struct drm_mm_node *hole; > > > - u64 end = node->start + node->size; > > > + u64 end; > > > u64 hole_start; > > > u64 hole_end; > > > > > > BUG_ON(node == NULL); > > > > > > + end = node->start + node->size; > > > + > > > /* Find the relevant hole to add our node to */ > > > drm_mm_for_each_hole(hole, mm, hole_start, hole_end) { > > > if (hole_start > node->start || hole_end < end) > > > -- > > > 2.1.4 > > > > Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com> Remove useless check instead? -Chris -- Chris Wilson, Intel Open Source Technology Centre ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] drm/mm: avoid possible null pointer dereference 2016-05-23 13:02 ` Chris Wilson @ 2016-05-23 13:38 ` Eric Engestrom 2016-05-23 13:46 ` Chris Wilson 0 siblings, 1 reply; 8+ messages in thread From: Eric Engestrom @ 2016-05-23 13:38 UTC (permalink / raw) To: Chris Wilson, Heinrich Schuchardt, linux-kernel, dri-devel On Mon, May 23, 2016 at 02:02:26PM +0100, Chris Wilson wrote: > On Mon, May 23, 2016 at 02:56:45PM +0200, Daniel Vetter wrote: > > On Mon, May 23, 2016 at 11:27:14AM +0100, Eric Engestrom wrote: > > > On Wed, May 18, 2016 at 10:17:19PM +0200, Heinrich Schuchardt wrote: > > > > Do not dereference node before the check if node is NULL. > > > > > > > > Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de> > > > > --- > > > > drivers/gpu/drm/drm_mm.c | 4 +++- > > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c > > > > index 04de6fd..cb39f45 100644 > > > > --- a/drivers/gpu/drm/drm_mm.c > > > > +++ b/drivers/gpu/drm/drm_mm.c > > > > @@ -179,12 +179,14 @@ static void drm_mm_insert_helper(struct drm_mm_node *hole_node, > > > > int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node) > > > > { > > > > struct drm_mm_node *hole; > > > > - u64 end = node->start + node->size; > > > > + u64 end; > > > > u64 hole_start; > > > > u64 hole_end; > > > > > > > > BUG_ON(node == NULL); > > > > > > > > + end = node->start + node->size; > > > > + > > > > /* Find the relevant hole to add our node to */ > > > > drm_mm_for_each_hole(hole, mm, hole_start, hole_end) { > > > > if (hole_start > node->start || hole_end < end) > > > > -- > > > > 2.1.4 > > > > > > Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com> > > Remove useless check instead? > -Chris I tend to prefer erring on the side of caution and have (too) many checks, especially simple ones like avoiding null dereferences. That said, BUG() might be too extreme. I'm not all that familiar with the code, but it doesn't seem like it would be an unrecoverable failure. WARN() instead? ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] drm/mm: avoid possible null pointer dereference 2016-05-23 13:38 ` Eric Engestrom @ 2016-05-23 13:46 ` Chris Wilson 2016-05-23 15:35 ` Eric Engestrom 0 siblings, 1 reply; 8+ messages in thread From: Chris Wilson @ 2016-05-23 13:46 UTC (permalink / raw) To: Eric Engestrom; +Cc: Heinrich Schuchardt, linux-kernel, dri-devel On Mon, May 23, 2016 at 02:38:29PM +0100, Eric Engestrom wrote: > On Mon, May 23, 2016 at 02:02:26PM +0100, Chris Wilson wrote: > > On Mon, May 23, 2016 at 02:56:45PM +0200, Daniel Vetter wrote: > > > On Mon, May 23, 2016 at 11:27:14AM +0100, Eric Engestrom wrote: > > > > On Wed, May 18, 2016 at 10:17:19PM +0200, Heinrich Schuchardt wrote: > > > > > Do not dereference node before the check if node is NULL. > > > > > > > > > > Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de> > > > > > --- > > > > > drivers/gpu/drm/drm_mm.c | 4 +++- > > > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > > > > > diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c > > > > > index 04de6fd..cb39f45 100644 > > > > > --- a/drivers/gpu/drm/drm_mm.c > > > > > +++ b/drivers/gpu/drm/drm_mm.c > > > > > @@ -179,12 +179,14 @@ static void drm_mm_insert_helper(struct drm_mm_node *hole_node, > > > > > int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node) > > > > > { > > > > > struct drm_mm_node *hole; > > > > > - u64 end = node->start + node->size; > > > > > + u64 end; > > > > > u64 hole_start; > > > > > u64 hole_end; > > > > > > > > > > BUG_ON(node == NULL); > > > > > > > > > > + end = node->start + node->size; > > > > > + > > > > > /* Find the relevant hole to add our node to */ > > > > > drm_mm_for_each_hole(hole, mm, hole_start, hole_end) { > > > > > if (hole_start > node->start || hole_end < end) > > > > > -- > > > > > 2.1.4 > > > > > > > > Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com> > > > > Remove useless check instead? > > -Chris > > I tend to prefer erring on the side of caution and have (too) many checks, > especially simple ones like avoiding null dereferences. BUG(node == NULL) is no more informative than hitting a GFP with *node. > That said, BUG() might be too extreme. I'm not all that familiar with > the code, but it doesn't seem like it would be an unrecoverable failure. > WARN() instead? It's a programming error, just as would be passing in mm == NULL. Mark up the function as requiring non-NULL parameters. -Chris -- Chris Wilson, Intel Open Source Technology Centre ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] drm/mm: avoid possible null pointer dereference 2016-05-23 13:46 ` Chris Wilson @ 2016-05-23 15:35 ` Eric Engestrom 2016-05-23 15:50 ` Chris Wilson 0 siblings, 1 reply; 8+ messages in thread From: Eric Engestrom @ 2016-05-23 15:35 UTC (permalink / raw) To: Chris Wilson, Heinrich Schuchardt, linux-kernel, dri-devel On Mon, May 23, 2016 at 02:46:59PM +0100, Chris Wilson wrote: > On Mon, May 23, 2016 at 02:38:29PM +0100, Eric Engestrom wrote: > > On Mon, May 23, 2016 at 02:02:26PM +0100, Chris Wilson wrote: > > > On Mon, May 23, 2016 at 02:56:45PM +0200, Daniel Vetter wrote: > > > > On Mon, May 23, 2016 at 11:27:14AM +0100, Eric Engestrom wrote: > > > > > On Wed, May 18, 2016 at 10:17:19PM +0200, Heinrich Schuchardt wrote: > > > > > > Do not dereference node before the check if node is NULL. > > > > > > > > > > > > Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de> > > > > > > --- > > > > > > drivers/gpu/drm/drm_mm.c | 4 +++- > > > > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > > > > > > > diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c > > > > > > index 04de6fd..cb39f45 100644 > > > > > > --- a/drivers/gpu/drm/drm_mm.c > > > > > > +++ b/drivers/gpu/drm/drm_mm.c > > > > > > @@ -179,12 +179,14 @@ static void drm_mm_insert_helper(struct drm_mm_node *hole_node, > > > > > > int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node) > > > > > > { > > > > > > struct drm_mm_node *hole; > > > > > > - u64 end = node->start + node->size; > > > > > > + u64 end; > > > > > > u64 hole_start; > > > > > > u64 hole_end; > > > > > > > > > > > > BUG_ON(node == NULL); > > > > > > > > > > > > + end = node->start + node->size; > > > > > > + > > > > > > /* Find the relevant hole to add our node to */ > > > > > > drm_mm_for_each_hole(hole, mm, hole_start, hole_end) { > > > > > > if (hole_start > node->start || hole_end < end) > > > > > > -- > > > > > > 2.1.4 > > > > > > > > > > Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com> > > > > > > Remove useless check instead? > > > -Chris > > > > I tend to prefer erring on the side of caution and have (too) many checks, > > especially simple ones like avoiding null dereferences. > > BUG(node == NULL) is no more informative than hitting a GFP with *node. Good point. > > > That said, BUG() might be too extreme. I'm not all that familiar with > > the code, but it doesn't seem like it would be an unrecoverable failure. > > WARN() instead? > > It's a programming error, just as would be passing in mm == NULL. Mark up > the function as requiring non-NULL parameters. > -Chris Using `__attribute__((nonnull))`? I approve of that idea, as I find those attributes extremely useful and try to get them used as much as possible at $DAYJOB. I have noticed however that this particular attribute isn't used much in the kernel (4 times that I could find with a simple grep), to the point of not even having a `__nonnull`. Any reason you know of? Cheers, Eric ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] drm/mm: avoid possible null pointer dereference 2016-05-23 15:35 ` Eric Engestrom @ 2016-05-23 15:50 ` Chris Wilson 0 siblings, 0 replies; 8+ messages in thread From: Chris Wilson @ 2016-05-23 15:50 UTC (permalink / raw) To: Eric Engestrom; +Cc: Heinrich Schuchardt, linux-kernel, dri-devel On Mon, May 23, 2016 at 04:35:53PM +0100, Eric Engestrom wrote: > On Mon, May 23, 2016 at 02:46:59PM +0100, Chris Wilson wrote: > > It's a programming error, just as would be passing in mm == NULL. Mark up > > the function as requiring non-NULL parameters. > > Using `__attribute__((nonnull))`? I approve of that idea, as I find > those attributes extremely useful and try to get them used as much as > possible at $DAYJOB. > > I have noticed however that this particular attribute isn't used much in > the kernel (4 times that I could find with a simple grep), to the point > of not even having a `__nonnull`. Any reason you know of? Not that I know of. Even more confusing is its use under tools but not being added to the main kernel. -Chris -- Chris Wilson, Intel Open Source Technology Centre ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2016-05-23 15:51 UTC | newest] Thread overview: 8+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2016-05-18 20:17 [PATCH] drm/mm: avoid possible null pointer dereference Heinrich Schuchardt 2016-05-23 10:27 ` Eric Engestrom 2016-05-23 12:56 ` Daniel Vetter 2016-05-23 13:02 ` Chris Wilson 2016-05-23 13:38 ` Eric Engestrom 2016-05-23 13:46 ` Chris Wilson 2016-05-23 15:35 ` Eric Engestrom 2016-05-23 15:50 ` Chris Wilson
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