[ Upstream commit bd2fccac61b40eaf08d9546acc9fef958bfe4763 ]
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: Sasha Levin <sashal@kernel.org>
[ Upstream commit 3d887d512494d678b17c57b835c32f4e48d34f26 ]
As drm_dp_get_mst_branch_device_by_guid() is called from
drm_dp_get_mst_branch_device_by_guid(), mstb parameter has to be checked,
otherwise NULL dereference may occur in the call to
the memcpy() and cause following:
[12579.365869] BUG: kernel NULL pointer dereference, address: 0000000000000049
[12579.365878] #PF: supervisor read access in kernel mode
[12579.365880] #PF: error_code(0x0000) - not-present page
[12579.365882] PGD 0 P4D 0
[12579.365887] Oops: 0000 [#1] PREEMPT SMP NOPTI
...
[12579.365895] Workqueue: events_long drm_dp_mst_up_req_work
[12579.365899] RIP: 0010:memcmp+0xb/0x29
[12579.365921] Call Trace:
[12579.365927] get_mst_branch_device_by_guid_helper+0x22/0x64
[12579.365930] drm_dp_mst_up_req_work+0x137/0x416
[12579.365933] process_one_work+0x1d0/0x419
[12579.365935] worker_thread+0x11a/0x289
[12579.365938] kthread+0x13e/0x14f
[12579.365941] ? process_one_work+0x419/0x419
[12579.365943] ? kthread_blkcg+0x31/0x31
[12579.365946] ret_from_fork+0x1f/0x30
As get_mst_branch_device_by_guid_helper() is recursive, moving condition
to the first line allow to remove a similar one for step over of NULL elements
inside a loop.
Fixes: 5e93b8208d3c ("drm/dp/mst: move GUID storage from mgr, port to only mst branch")
Cc: <stable@vger.kernel.org> # 4.14+
Signed-off-by: Lukasz Majczak <lma@semihalf.com>
Reviewed-by: Radoslaw Biernacki <rad@chromium.org>
Signed-off-by: Manasi Navare <navaremanasi@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230922063410.23626-1-lma@semihalf.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
