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drm: fd.o Bug #7595: Avoid u32 overflows in radeon_check_and_fixup_offset(). 

The overflows could cause valid offsets to get rejected under some
circumstances, e.g. when the framebuffer resides at the very end of the card's
address space.

Signed-off-by: Dave Airlie <airlied@linux.ie>
This commit is contained in:
Michel Daenzer 2006-09-22 04:12:11 +10:00 committed by Dave Airlie
parent 47cc140931
commit 214ff13d9e
1 changed files with 12 additions and 13 deletions
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25
drivers/char/drm/radeon_state.c
View File

@ -42,7 +42,11 @@ static __inline__ int radeon_check_and_fixup_offset(drm_radeon_private_t *
drm_file_t * filp_priv, drm_file_t * filp_priv,
u32 *offset) u32 *offset)
{ {
u32 off = *offset; u64 off = *offset;
u32 fb_start = dev_priv->fb_location;
u32 fb_end = fb_start + dev_priv->fb_size - 1;
u32 gart_start = dev_priv->gart_vm_start;
u32 gart_end = gart_start + dev_priv->gart_size - 1;
struct drm_radeon_driver_file_fields *radeon_priv; struct drm_radeon_driver_file_fields *radeon_priv;
/* Hrm ... the story of the offset ... So this function converts /* Hrm ... the story of the offset ... So this function converts
@ -62,10 +66,8 @@ static __inline__ int radeon_check_and_fixup_offset(drm_radeon_private_t *
/* First, the best case, the offset already lands in either the /* First, the best case, the offset already lands in either the
* framebuffer or the GART mapped space * framebuffer or the GART mapped space
*/ */
if ((off >= dev_priv->fb_location && if ((off >= fb_start && off <= fb_end) ||
off < (dev_priv->fb_location + dev_priv->fb_size)) || (off >= gart_start && off <= gart_end))
(off >= dev_priv->gart_vm_start &&
off < (dev_priv->gart_vm_start + dev_priv->gart_size)))
return 0; return 0;
/* Ok, that didn't happen... now check if we have a zero based /* Ok, that didn't happen... now check if we have a zero based
@ -78,16 +80,13 @@ static __inline__ int radeon_check_and_fixup_offset(drm_radeon_private_t *
} }
/* Finally, assume we aimed at a GART offset if beyond the fb */ /* Finally, assume we aimed at a GART offset if beyond the fb */
if (off > (dev_priv->fb_location + dev_priv->fb_size)) if (off > fb_end)
off = off - (dev_priv->fb_location + dev_priv->fb_size) + off = off - fb_end - 1 + gart_start;
dev_priv->gart_vm_start;
/* Now recheck and fail if out of bounds */ /* Now recheck and fail if out of bounds */
if ((off >= dev_priv->fb_location && if ((off >= fb_start && off <= fb_end) ||
off < (dev_priv->fb_location + dev_priv->fb_size)) || (off >= gart_start && off <= gart_end)) {
(off >= dev_priv->gart_vm_start && DRM_DEBUG("offset fixed up to 0x%x\n", (unsigned int)off);
off < (dev_priv->gart_vm_start + dev_priv->gart_size))) {
DRM_DEBUG("offset fixed up to 0x%x\n", off);
*offset = off; *offset = off;
return 0; return 0;
} }