On Mon, Jun 22, 2026 at 6:39 AM Jani Nikula <[email protected]> wrote: > > On Wed, 17 Jun 2026, Jani Nikula <[email protected]> wrote: > > On Mon, 15 Jun 2026, Xiang Mei <[email protected]> wrote: > >> drm_parse_tiled_block() casts the DisplayID block to a > >> struct displayid_tiled_block and reads the full fixed layout up to > >> tile->topology_id[7] without checking block->num_bytes. The DisplayID > >> iterator only validates the declared payload length, so a crafted EDID > >> can advertise a tiled-display block (tag DATA_BLOCK_TILED_DISPLAY, or > >> DATA_BLOCK_2_TILED_DISPLAY_TOPOLOGY for v2.0) with a small num_bytes at > >> the end of a DisplayID extension. The read then runs past the end of the > >> exact-sized kmemdup()'d EDID allocation, a heap out-of-bounds read. > >> > >> Reject blocks shorter than the spec's 22-byte tiled payload before > >> reading the fixed struct, as drm_parse_vesa_mso_data() already does. > >> > >> BUG: KASAN: slab-out-of-bounds in drm_edid_connector_update > >> Read of size 2 at addr ffff888010077700 by task exploit/147 > >> dump_stack_lvl (lib/dump_stack.c:94 ...) > >> print_report (mm/kasan/report.c:378 ...) > >> kasan_report (mm/kasan/report.c:595) > >> drm_edid_connector_update (drivers/gpu/drm/drm_edid.c:7581) > >> bochs_connector_helper_get_modes (drivers/gpu/drm/tiny/bochs.c:574) > >> drm_helper_probe_single_connector_modes > >> (drivers/gpu/drm/drm_probe_helper.c:426) > >> status_store (drivers/gpu/drm/drm_sysfs.c:219) > >> ... > >> vfs_write (fs/read_write.c:595 fs/read_write.c:688) > >> ksys_write (fs/read_write.c:740) > >> > >> Fixes: 40d9b043a89e ("drm/connector: store tile information from displayid > >> (v3)") > >> Reported-by: Weiming Shi <[email protected]> > >> Assisted-by: Claude:claude-opus-4-8 > >> Signed-off-by: Xiang Mei <[email protected]> > > > > Reviewed-by: Jani Nikula <[email protected]> > > And pushed to drm-misc-fixes, thanks for the patch. > Thanks for your review!
Best, Xiang > BR, > Jani. > > > > > >> --- > >> v2: use 22 instead of sizeof, based on the topology_id[9] fix: > >> https://lore.kernel.org/r/[email protected] > >> > >> drivers/gpu/drm/drm_edid.c | 8 ++++++++ > >> 1 file changed, 8 insertions(+) > >> > >> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c > >> index 404208bf23a6..df3c25bac761 100644 > >> --- a/drivers/gpu/drm/drm_edid.c > >> +++ b/drivers/gpu/drm/drm_edid.c > >> @@ -7575,6 +7575,14 @@ static void drm_parse_tiled_block(struct > >> drm_connector *connector, > >> u8 num_v_tile, num_h_tile; > >> struct drm_tile_group *tg; > >> > >> + /* tiled block payload per spec: cap 1 + topo 3 + size 4 + bezel 5 + > >> id 9 = 22 */ > >> + if (block->num_bytes < 22) { > >> + drm_dbg_kms(connector->dev, > >> + "[CONNECTOR:%d:%s] Unexpected tiled block size > >> %u\n", > >> + connector->base.id, connector->name, > >> block->num_bytes); > >> + return; > >> + } > >> + > >> w = tile->tile_size[0] | tile->tile_size[1] << 8; > >> h = tile->tile_size[2] | tile->tile_size[3] << 8; > > -- > Jani Nikula, Intel
