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780fa184d4
commit bd2fccac61b40eaf08d9546acc9fef958bfe4763 upstream.
Fix the MST sideband message body length check, which must be at least 1
byte accounting for the message body CRC (aka message data CRC) at the
end of the message.
This fixes a case where an MST branch device returns a header with a
correct header CRC (indicating a correctly received body length), with
the body length being incorrectly set to 0. This will later lead to a
memory corruption in drm_dp_sideband_append_payload() and the following
errors in dmesg:
UBSAN: array-index-out-of-bounds in drivers/gpu/drm/display/drm_dp_mst_topology.c:786:25
index -1 is out of range for type 'u8 [48]'
Call Trace:
drm_dp_sideband_append_payload+0x33d/0x350 [drm_display_helper]
drm_dp_get_one_sb_msg+0x3ce/0x5f0 [drm_display_helper]
drm_dp_mst_hpd_irq_handle_event+0xc8/0x1580 [drm_display_helper]
memcpy: detected field-spanning write (size 18446744073709551615) of single field "&msg->msg[msg->curlen]" at drivers/gpu/drm/display/drm_dp_mst_topology.c:791 (size 256)
Call Trace:
drm_dp_sideband_append_payload+0x324/0x350 [drm_display_helper]
drm_dp_get_one_sb_msg+0x3ce/0x5f0 [drm_display_helper]
drm_dp_mst_hpd_irq_handle_event+0xc8/0x1580 [drm_display_helper]
Cc: <stable@vger.kernel.org>
Cc: Lyude Paul <lyude@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241125205314.1725887-1-imre.deak@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
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