Re: [PATCH] drm/nouveau/nvif: Avoid build error due to potential integer overflows
On 5/18/24 18:19, Joe Perches wrote:
On Sat, 2024-05-18 at 11:23 -0700, Guenter Roeck wrote:
On 5/18/24 10:32, Kees Cook wrote:
[]
I think the INT_MAX test is actually better in this case because
nvif_object_ioctl()'s size argument is u32:
ret = nvif_object_ioctl(object, args, sizeof(*args) + size, NULL);
So that could wrap around, even though the allocation may not.
Better yet, since "sizeof(*args) + size" is repeated 3 times in the
function, I'd recommend:
...
u32 args_size;
if (check_add_overflow(sizeof(*args), size, _size))
return -ENOMEM;
if (args_size > sizeof(stack)) {
if (!(args = kmalloc(args_size, GFP_KERNEL)))
trivia:
More typical kernel style would use separate alloc and test
args = kmalloc(args_size, GFP_KERNEL);
if (!args)
Sure, I can do that as well. I'll wait a couple of days though before
sending v3 in case there are more change requests.
Guenter
Re: [PATCH] drm/nouveau/nvif: Avoid build error due to potential integer overflows
On Sat, 2024-05-18 at 11:23 -0700, Guenter Roeck wrote:
> On 5/18/24 10:32, Kees Cook wrote:
>
[]
> > I think the INT_MAX test is actually better in this case because
> > nvif_object_ioctl()'s size argument is u32:
> >
> > ret = nvif_object_ioctl(object, args, sizeof(*args) + size, NULL);
> >
> >
> > So that could wrap around, even though the allocation may not.
> >
> > Better yet, since "sizeof(*args) + size" is repeated 3 times in the
> > function, I'd recommend:
> >
> > ...
> > u32 args_size;
> >
> > if (check_add_overflow(sizeof(*args), size, _size))
> > return -ENOMEM;
> > if (args_size > sizeof(stack)) {
> > if (!(args = kmalloc(args_size, GFP_KERNEL)))
trivia:
More typical kernel style would use separate alloc and test
args = kmalloc(args_size, GFP_KERNEL);
if (!args)
> > return -ENOMEM;
> > } else {
> > args = (void *)stack;
> > }
> > ...
> > ret = nvif_object_ioctl(object, args, args_size, NULL);
> >
> > This will catch the u32 overflow to nvif_object_ioctl(), catch an
> > allocation underflow on 32-bits systems, and make the code more
> > readable. :)
> >
>
> Makes sense. I'll change that and send v2.
>
> Thanks,
> Guenter
>
>
Re: [PATCH] drm/nouveau/nvif: Avoid build error due to potential integer overflows
On 5/18/24 10:32, Kees Cook wrote:
On Sat, May 18, 2024 at 06:54:36PM +0200, Christophe JAILLET wrote:
(adding linux-harden...@vger.kernel.org)
Le 18/05/2024 à 16:37, Guenter Roeck a écrit :
Trying to build parisc:allmodconfig with gcc 12.x or later results
in the following build error.
drivers/gpu/drm/nouveau/nvif/object.c: In function 'nvif_object_mthd':
drivers/gpu/drm/nouveau/nvif/object.c:161:9: error:
'memcpy' accessing 4294967264 or more bytes at offsets 0 and 32
overlaps 6442450881 bytes at offset -2147483617 [-Werror=restrict]
161 | memcpy(data, args->mthd.data, size);
| ^~~
drivers/gpu/drm/nouveau/nvif/object.c: In function 'nvif_object_ctor':
drivers/gpu/drm/nouveau/nvif/object.c:298:17: error:
'memcpy' accessing 4294967240 or more bytes at offsets 0 and 56
overlaps 6442450833 bytes at offset -2147483593 [-Werror=restrict]
298 | memcpy(data, args->new.data, size);
gcc assumes that 'sizeof(*args) + size' can overflow, which would result
in the problem.
The problem is not new, only it is now no longer a warning but an error since
W=1
has been enabled for the drm subsystem and since Werror is enabled for test
builds.
Rearrange arithmetic and add extra size checks to avoid the overflow.
Fixes: a61ddb4393ad ("drm: enable (most) W=1 warnings by default across the
subsystem")
Cc: Javier Martinez Canillas
Cc: Jani Nikula
Cc: Thomas Zimmermann
Cc: Danilo Krummrich
Cc: Maxime Ripard
Signed-off-by: Guenter Roeck
---
checkpatch complains about the line length in the description and the
(pre-existing)
assignlemts in if conditions, but I did not want to split lines in the
description
or rearrange the code further.
I don't know why I only see the problem with parisc builds (at least so far).
drivers/gpu/drm/nouveau/nvif/object.c | 8 +---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/nvif/object.c
b/drivers/gpu/drm/nouveau/nvif/object.c
index 4d1aaee8fe15..baf623a48874 100644
--- a/drivers/gpu/drm/nouveau/nvif/object.c
+++ b/drivers/gpu/drm/nouveau/nvif/object.c
@@ -145,8 +145,9 @@ nvif_object_mthd(struct nvif_object *object, u32 mthd, void
*data, u32 size)
u8 stack[128];
int ret;
- if (sizeof(*args) + size > sizeof(stack)) {
- if (!(args = kmalloc(sizeof(*args) + size, GFP_KERNEL)))
+ if (size > sizeof(stack) - sizeof(*args)) {
+ if (size > INT_MAX ||
+ !(args = kmalloc(sizeof(*args) + size, GFP_KERNEL)))
Hi,
Would it be cleaner or better to use size_add(sizeof(*args), size)?
I think the INT_MAX test is actually better in this case because
nvif_object_ioctl()'s size argument is u32:
ret = nvif_object_ioctl(object, args, sizeof(*args) + size, NULL);
So that could wrap around, even though the allocation may not.
Better yet, since "sizeof(*args) + size" is repeated 3 times in the
function, I'd recommend:
...
u32 args_size;
if (check_add_overflow(sizeof(*args), size, _size))
return -ENOMEM;
if (args_size > sizeof(stack)) {
if (!(args = kmalloc(args_size, GFP_KERNEL)))
return -ENOMEM;
} else {
args = (void *)stack;
}
...
ret = nvif_object_ioctl(object, args, args_size, NULL);
This will catch the u32 overflow to nvif_object_ioctl(), catch an
allocation underflow on 32-bits systems, and make the code more
readable. :)
Makes sense. I'll change that and send v2.
Thanks,
Guenter
Re: [PATCH] drm/nouveau/nvif: Avoid build error due to potential integer overflows
On Sat, May 18, 2024 at 06:54:36PM +0200, Christophe JAILLET wrote:
> (adding linux-harden...@vger.kernel.org)
>
>
> Le 18/05/2024 à 16:37, Guenter Roeck a écrit :
> > Trying to build parisc:allmodconfig with gcc 12.x or later results
> > in the following build error.
> >
> > drivers/gpu/drm/nouveau/nvif/object.c: In function 'nvif_object_mthd':
> > drivers/gpu/drm/nouveau/nvif/object.c:161:9: error:
> > 'memcpy' accessing 4294967264 or more bytes at offsets 0 and 32
> > overlaps 6442450881 bytes at offset -2147483617 [-Werror=restrict]
> >161 | memcpy(data, args->mthd.data, size);
> >| ^~~
> > drivers/gpu/drm/nouveau/nvif/object.c: In function 'nvif_object_ctor':
> > drivers/gpu/drm/nouveau/nvif/object.c:298:17: error:
> > 'memcpy' accessing 4294967240 or more bytes at offsets 0 and 56
> > overlaps 6442450833 bytes at offset -2147483593 [-Werror=restrict]
> >298 | memcpy(data, args->new.data, size);
> >
> > gcc assumes that 'sizeof(*args) + size' can overflow, which would result
> > in the problem.
> >
> > The problem is not new, only it is now no longer a warning but an error
> > since W=1
> > has been enabled for the drm subsystem and since Werror is enabled for test
> > builds.
> >
> > Rearrange arithmetic and add extra size checks to avoid the overflow.
> >
> > Fixes: a61ddb4393ad ("drm: enable (most) W=1 warnings by default across the
> > subsystem")
> > Cc: Javier Martinez Canillas
> >
> > Cc: Jani Nikula
> > Cc: Thomas Zimmermann
> > Cc: Danilo Krummrich
> > Cc: Maxime Ripard
> > Signed-off-by: Guenter Roeck
> > ---
> > checkpatch complains about the line length in the description and the
> > (pre-existing)
> > assignlemts in if conditions, but I did not want to split lines in the
> > description
> > or rearrange the code further.
> >
> > I don't know why I only see the problem with parisc builds (at least so
> > far).
> >
> > drivers/gpu/drm/nouveau/nvif/object.c | 8 +---
> > 1 file changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/nouveau/nvif/object.c
> > b/drivers/gpu/drm/nouveau/nvif/object.c
> > index 4d1aaee8fe15..baf623a48874 100644
> > --- a/drivers/gpu/drm/nouveau/nvif/object.c
> > +++ b/drivers/gpu/drm/nouveau/nvif/object.c
> > @@ -145,8 +145,9 @@ nvif_object_mthd(struct nvif_object *object, u32 mthd,
> > void *data, u32 size)
> > u8 stack[128];
> > int ret;
> > - if (sizeof(*args) + size > sizeof(stack)) {
> > - if (!(args = kmalloc(sizeof(*args) + size, GFP_KERNEL)))
> > + if (size > sizeof(stack) - sizeof(*args)) {
> > + if (size > INT_MAX ||
> > + !(args = kmalloc(sizeof(*args) + size, GFP_KERNEL)))
>
> Hi,
>
> Would it be cleaner or better to use size_add(sizeof(*args), size)?
I think the INT_MAX test is actually better in this case because
nvif_object_ioctl()'s size argument is u32:
ret = nvif_object_ioctl(object, args, sizeof(*args) + size, NULL);
So that could wrap around, even though the allocation may not.
Better yet, since "sizeof(*args) + size" is repeated 3 times in the
function, I'd recommend:
...
u32 args_size;
if (check_add_overflow(sizeof(*args), size, _size))
return -ENOMEM;
if (args_size > sizeof(stack)) {
if (!(args = kmalloc(args_size, GFP_KERNEL)))
return -ENOMEM;
} else {
args = (void *)stack;
}
...
ret = nvif_object_ioctl(object, args, args_size, NULL);
This will catch the u32 overflow to nvif_object_ioctl(), catch an
allocation underflow on 32-bits systems, and make the code more
readable. :)
-Kees
--
Kees Cook
Re: [PATCH] drm/nouveau/nvif: Avoid build error due to potential integer overflows
(adding linux-harden...@vger.kernel.org)
Le 18/05/2024 à 16:37, Guenter Roeck a écrit :
Trying to build parisc:allmodconfig with gcc 12.x or later results
in the following build error.
drivers/gpu/drm/nouveau/nvif/object.c: In function 'nvif_object_mthd':
drivers/gpu/drm/nouveau/nvif/object.c:161:9: error:
'memcpy' accessing 4294967264 or more bytes at offsets 0 and 32
overlaps 6442450881 bytes at offset -2147483617 [-Werror=restrict]
161 | memcpy(data, args->mthd.data, size);
| ^~~
drivers/gpu/drm/nouveau/nvif/object.c: In function 'nvif_object_ctor':
drivers/gpu/drm/nouveau/nvif/object.c:298:17: error:
'memcpy' accessing 4294967240 or more bytes at offsets 0 and 56
overlaps 6442450833 bytes at offset -2147483593 [-Werror=restrict]
298 | memcpy(data, args->new.data, size);
gcc assumes that 'sizeof(*args) + size' can overflow, which would result
in the problem.
The problem is not new, only it is now no longer a warning but an error since
W=1
has been enabled for the drm subsystem and since Werror is enabled for test
builds.
Rearrange arithmetic and add extra size checks to avoid the overflow.
Fixes: a61ddb4393ad ("drm: enable (most) W=1 warnings by default across the
subsystem")
Cc: Javier Martinez Canillas
Cc: Jani Nikula
Cc: Thomas Zimmermann
Cc: Danilo Krummrich
Cc: Maxime Ripard
Signed-off-by: Guenter Roeck
---
checkpatch complains about the line length in the description and the
(pre-existing)
assignlemts in if conditions, but I did not want to split lines in the
description
or rearrange the code further.
I don't know why I only see the problem with parisc builds (at least so far).
drivers/gpu/drm/nouveau/nvif/object.c | 8 +---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/nvif/object.c
b/drivers/gpu/drm/nouveau/nvif/object.c
index 4d1aaee8fe15..baf623a48874 100644
--- a/drivers/gpu/drm/nouveau/nvif/object.c
+++ b/drivers/gpu/drm/nouveau/nvif/object.c
@@ -145,8 +145,9 @@ nvif_object_mthd(struct nvif_object *object, u32 mthd, void
*data, u32 size)
u8 stack[128];
int ret;
- if (sizeof(*args) + size > sizeof(stack)) {
- if (!(args = kmalloc(sizeof(*args) + size, GFP_KERNEL)))
+ if (size > sizeof(stack) - sizeof(*args)) {
+ if (size > INT_MAX ||
+ !(args = kmalloc(sizeof(*args) + size, GFP_KERNEL)))
Hi,
Would it be cleaner or better to use size_add(sizeof(*args), size)?
return -ENOMEM;
} else {
args = (void *)stack;
@@ -276,7 +277,8 @@ nvif_object_ctor(struct nvif_object *parent, const char
*name, u32 handle,
object->map.size = 0;
if (parent) {
- if (!(args = kmalloc(sizeof(*args) + size, GFP_KERNEL))) {
+ if (size > INT_MAX ||
+ !(args = kmalloc(sizeof(*args) + size, GFP_KERNEL))) {
Same.
CJ
nvif_object_dtor(object);
return -ENOMEM;
}
[PATCH] drm/nouveau/nvif: Avoid build error due to potential integer overflows
Trying to build parisc:allmodconfig with gcc 12.x or later results
in the following build error.
drivers/gpu/drm/nouveau/nvif/object.c: In function 'nvif_object_mthd':
drivers/gpu/drm/nouveau/nvif/object.c:161:9: error:
'memcpy' accessing 4294967264 or more bytes at offsets 0 and 32
overlaps 6442450881 bytes at offset -2147483617 [-Werror=restrict]
161 | memcpy(data, args->mthd.data, size);
| ^~~
drivers/gpu/drm/nouveau/nvif/object.c: In function 'nvif_object_ctor':
drivers/gpu/drm/nouveau/nvif/object.c:298:17: error:
'memcpy' accessing 4294967240 or more bytes at offsets 0 and 56
overlaps 6442450833 bytes at offset -2147483593 [-Werror=restrict]
298 | memcpy(data, args->new.data, size);
gcc assumes that 'sizeof(*args) + size' can overflow, which would result
in the problem.
The problem is not new, only it is now no longer a warning but an error since
W=1
has been enabled for the drm subsystem and since Werror is enabled for test
builds.
Rearrange arithmetic and add extra size checks to avoid the overflow.
Fixes: a61ddb4393ad ("drm: enable (most) W=1 warnings by default across the
subsystem")
Cc: Javier Martinez Canillas
Cc: Jani Nikula
Cc: Thomas Zimmermann
Cc: Danilo Krummrich
Cc: Maxime Ripard
Signed-off-by: Guenter Roeck
---
checkpatch complains about the line length in the description and the
(pre-existing)
assignlemts in if conditions, but I did not want to split lines in the
description
or rearrange the code further.
I don't know why I only see the problem with parisc builds (at least so far).
drivers/gpu/drm/nouveau/nvif/object.c | 8 +---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/nouveau/nvif/object.c
b/drivers/gpu/drm/nouveau/nvif/object.c
index 4d1aaee8fe15..baf623a48874 100644
--- a/drivers/gpu/drm/nouveau/nvif/object.c
+++ b/drivers/gpu/drm/nouveau/nvif/object.c
@@ -145,8 +145,9 @@ nvif_object_mthd(struct nvif_object *object, u32 mthd, void
*data, u32 size)
u8 stack[128];
int ret;
- if (sizeof(*args) + size > sizeof(stack)) {
- if (!(args = kmalloc(sizeof(*args) + size, GFP_KERNEL)))
+ if (size > sizeof(stack) - sizeof(*args)) {
+ if (size > INT_MAX ||
+ !(args = kmalloc(sizeof(*args) + size, GFP_KERNEL)))
return -ENOMEM;
} else {
args = (void *)stack;
@@ -276,7 +277,8 @@ nvif_object_ctor(struct nvif_object *parent, const char
*name, u32 handle,
object->map.size = 0;
if (parent) {
- if (!(args = kmalloc(sizeof(*args) + size, GFP_KERNEL))) {
+ if (size > INT_MAX ||
+ !(args = kmalloc(sizeof(*args) + size, GFP_KERNEL))) {
nvif_object_dtor(object);
return -ENOMEM;
}
--
2.39.2
