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drm/vc4_validate: Remove VLA usage 

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>
Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20180313143151.GA27486@embeddedgus
This commit is contained in:
Gustavo A. R. Silva 2018-03-13 09:31:51 -05:00 committed by Eric Anholt
parent 2f0e9d8049
commit 0126b23c55
1 changed files with 1 additions and 1 deletions
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2
drivers/gpu/drm/vc4/vc4_validate.c
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@ -753,7 +753,7 @@ validate_gl_shader_rec(struct drm_device *dev,
28, /* cs */ 28, /* cs */
}; };
uint32_t shader_reloc_count = ARRAY_SIZE(shader_reloc_offsets); 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; uint32_t nr_attributes, nr_relocs, packet_size;
int i; int i;