| Message ID | 20180313143151.GA27486@embeddedgus (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
"Gustavo A. R. Silva" <gustavo@embeddedor.com> writes: > In preparation to enabling -Wvla, remove VLA. In this particular > case use macro ARRAY_SIZE so the length of array _bo_ can be > computed at preprocessing time. > > The use of stack Variable Length Arrays needs to be avoided, as they > can be a vector for stack exhaustion, which can be both a runtime bug > or a security flaw. Also, in general, as code evolves it is easy to > lose track of how big a VLA can get. Thus, we can end up having runtime > failures that are hard to debug. > > Also, fixed as part of the directive to remove all VLAs from > the kernel: https://lkml.org/lkml/2018/3/7/621 > > Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> > --- > drivers/gpu/drm/vc4/vc4_validate.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/vc4/vc4_validate.c b/drivers/gpu/drm/vc4/vc4_validate.c > index 2db485a..eec76af 100644 > --- a/drivers/gpu/drm/vc4/vc4_validate.c > +++ b/drivers/gpu/drm/vc4/vc4_validate.c > @@ -753,7 +753,7 @@ validate_gl_shader_rec(struct drm_device *dev, > 28, /* cs */ > }; > uint32_t shader_reloc_count = ARRAY_SIZE(shader_reloc_offsets); > - struct drm_gem_cma_object *bo[shader_reloc_count + 8]; > + struct drm_gem_cma_object *bo[ARRAY_SIZE(shader_reloc_offsets) + 8]; > uint32_t nr_attributes, nr_relocs, packet_size; > int i; > > -- > 2.7.4 It's a shame that the compiler is warning about this when it's obviously a compile-time constant. Regardless, reviewed and applied.
diff --git a/drivers/gpu/drm/vc4/vc4_validate.c b/drivers/gpu/drm/vc4/vc4_validate.c index 2db485a..eec76af 100644 --- a/drivers/gpu/drm/vc4/vc4_validate.c +++ b/drivers/gpu/drm/vc4/vc4_validate.c @@ -753,7 +753,7 @@ validate_gl_shader_rec(struct drm_device *dev, 28, /* cs */ }; uint32_t shader_reloc_count = ARRAY_SIZE(shader_reloc_offsets); - struct drm_gem_cma_object *bo[shader_reloc_count + 8]; + struct drm_gem_cma_object *bo[ARRAY_SIZE(shader_reloc_offsets) + 8]; uint32_t nr_attributes, nr_relocs, packet_size; int i;
In preparation to enabling -Wvla, remove VLA. In this particular case use macro ARRAY_SIZE so the length of array _bo_ can be computed at preprocessing time. The use of stack Variable Length Arrays needs to be avoided, as they can be a vector for stack exhaustion, which can be both a runtime bug or a security flaw. Also, in general, as code evolves it is easy to lose track of how big a VLA can get. Thus, we can end up having runtime failures that are hard to debug. Also, fixed as part of the directive to remove all VLAs from the kernel: https://lkml.org/lkml/2018/3/7/621 Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> --- drivers/gpu/drm/vc4/vc4_validate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)