From cd67d226ebd909d239d2c6e5a6abd6e2a338d1cd Mon Sep 17 00:00:00 2001 From: Jani Nikula Date: Thu, 17 Sep 2015 16:42:07 +0300 Subject: [PATCH] drm/i915/bios: handle MIPI Sequence Block v3+ gracefully The VBT MIPI Sequence Block version 3 has forward incompatible changes: First, the block size in the header has been specified reserved, and the actual size is a separate 32-bit value within the block. The current find_section() function to will only look at the size in the block header, and, depending on what's in that now reserved size field, continue looking for other sections in the wrong place. Fix this by taking the new block size field into account. This will ensure that the lookups for other sections will work properly, as long as the new 32-bit size does not go beyond the opregion VBT mailbox size. Second, the contents of the block have been completely changed. Gracefully refuse parsing the yet unknown data version. Cc: Deepak M Cc: stable@vger.kernel.org Reviewed-by: Deepak M Signed-off-by: Jani Nikula --- drivers/gpu/drm/i915/intel_bios.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c index b3e437b3bb54..c19e669ffe50 100644 --- a/drivers/gpu/drm/i915/intel_bios.c +++ b/drivers/gpu/drm/i915/intel_bios.c @@ -42,7 +42,7 @@ find_section(const void *_bdb, int section_id) const struct bdb_header *bdb = _bdb; const u8 *base = _bdb; int index = 0; - u16 total, current_size; + u32 total, current_size; u8 current_id; /* skip to first section */ @@ -57,6 +57,10 @@ find_section(const void *_bdb, int section_id) current_size = *((const u16 *)(base + index)); index += 2; + /* The MIPI Sequence Block v3+ has a separate size field. */ + if (current_id == BDB_MIPI_SEQUENCE && *(base + index) >= 3) + current_size = *((const u32 *)(base + index + 1)); + if (index + current_size > total) return NULL; @@ -799,6 +803,12 @@ parse_mipi(struct drm_i915_private *dev_priv, const struct bdb_header *bdb) return; } + /* Fail gracefully for forward incompatible sequence block. */ + if (sequence->version >= 3) { + DRM_ERROR("Unable to parse MIPI Sequence Block v3+\n"); + return; + } + DRM_DEBUG_DRIVER("Found MIPI sequence block\n"); block_size = get_blocksize(sequence); -- GitLab