[PATCH 07/14] drm/i915: Validate BDB section before reading

Rodrigo Vivi
2014-04-18T21:04:43Z

From: Chris Wilson <chris@chris-wilson.co.uk>

Make sure that the whole BDB section is within the MMIO region prior to
accessing it contents. That we don't read outside of the secion is left
up to the individual section parsers.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
---
drivers/gpu/drm/i915/intel_bios.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index fc9e806..2945f57 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -49,13 +49,19 @@ find_section(struct bdb_header *bdb, int section_id)
total = bdb->bdb_size;

/* walk the sections looking for section_id */
- while (index < total) {
+ while (index + 3 < total) {
current_id = *(base + index);
index++;
+
current_size = *((u16 *)(base + index));
index += 2;
+
+ if (index + current_size > total)
+ return NULL;
+
if (current_id == section_id)
return base + index;
+
index += current_size;
}

--
1.8.3.1