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>
diff --git a/drivers/char/drm/radeon_state.c b/drivers/char/drm/radeon_state.c
index 0433ff8..bcfa151 100644
--- a/drivers/char/drm/radeon_state.c
+++ b/drivers/char/drm/radeon_state.c
@@ -42,7 +42,11 @@
drm_file_t * filp_priv,
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;
/* Hrm ... the story of the offset ... So this function converts
@@ -62,10 +66,8 @@
/* First, the best case, the offset already lands in either the
* framebuffer or the GART mapped space
*/
- if ((off >= dev_priv->fb_location &&
- off < (dev_priv->fb_location + dev_priv->fb_size)) ||
- (off >= dev_priv->gart_vm_start &&
- off < (dev_priv->gart_vm_start + dev_priv->gart_size)))
+ if ((off >= fb_start && off <= fb_end) ||
+ (off >= gart_start && off <= gart_end))
return 0;
/* Ok, that didn't happen... now check if we have a zero based
@@ -78,16 +80,13 @@
}
/* Finally, assume we aimed at a GART offset if beyond the fb */
- if (off > (dev_priv->fb_location + dev_priv->fb_size))
- off = off - (dev_priv->fb_location + dev_priv->fb_size) +
- dev_priv->gart_vm_start;
+ if (off > fb_end)
+ off = off - fb_end - 1 + gart_start;
/* Now recheck and fail if out of bounds */
- if ((off >= dev_priv->fb_location &&
- off < (dev_priv->fb_location + dev_priv->fb_size)) ||
- (off >= dev_priv->gart_vm_start &&
- off < (dev_priv->gart_vm_start + dev_priv->gart_size))) {
- DRM_DEBUG("offset fixed up to 0x%x\n", off);
+ if ((off >= fb_start && off <= fb_end) ||
+ (off >= gart_start && off <= gart_end)) {
+ DRM_DEBUG("offset fixed up to 0x%x\n", (unsigned int)off);
*offset = off;
return 0;
}