Reviewed-by: Deepak M <[email protected]>
>-----Original Message----- >From: Daniel Vetter [mailto:[email protected]] On Behalf Of Daniel >Vetter >Sent: Wednesday, September 23, 2015 7:02 PM >To: Nikula, Jani >Cc: [email protected]; Deepak, M >Subject: Re: [Intel-gfx] [PATCH] drm/i915/bios: handle MIPI Sequence Block >v3+ gracefully > >On Thu, Sep 17, 2015 at 04:42:07PM +0300, Jani Nikula wrote: >> 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 <[email protected]> >> Cc: [email protected] >> Signed-off-by: Jani Nikula <[email protected]> > >Deepak, ping for review. >-Daniel > >> --- >> 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 c8acc2952f82..68421c273c8c 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); >> -- >> 2.1.4 >> >> _______________________________________________ >> Intel-gfx mailing list >> [email protected] >> http://lists.freedesktop.org/mailman/listinfo/intel-gfx > >-- >Daniel Vetter >Software Engineer, Intel Corporation >http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/intel-gfx
