CVE-2024-56616

In the Linux kernel, the following vulnerability has been resolved:

drm/dp_mst: Fix MST sideband message body length check

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]

Affected Software

References

• https://git.kernel.org/stable/c/1fc1f32c4a3421b9d803f18ec3ef49db2fb5d5ef
• https://git.kernel.org/stable/c/780fa184d4dc38ad6c4fded345ab8f9be7a63e96
• https://git.kernel.org/stable/c/bd2fccac61b40eaf08d9546acc9fef958bfe4763
• https://git.kernel.org/stable/c/c58947a8d4a500902597ee1dbadf0518d7ff8801