mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-09-16 00:59:28 -05:00
Code Issues Packages Projects Releases Wiki Activity

drm/amd/display: clamp DMUB AUX reply length to payload buffer

Browse Source 
[Why]
amdgpu_dm_process_dmub_aux_transfer_sync() copies p_notify->aux_reply.length
bytes into payload->data without clamping. payload->data is typically a 16-byte
DPCD scratch buffer, while aux_reply.length is echoed from the sink via the DMUB
ring. While this is clamped by DMUB it's prudent to ensure we validate
this in the driver as well.

[How]
Clamp the copy to sizeof(aux_reply.data), the scratch buffer the reply was read
into, and use that for both the memcpy and the return value. For regular
transfers additionally clamp to payload->length to cover callers whose
destination buffer is smaller than 16 bytes. The write-status-update retry path
(dce_aux_transfer_with_retries) deliberately zeroes payload->length while still
expecting the partial-write status byte, so that bound is skipped in that case
to avoid dropping the reply. Also guard against a NULL payload->data.

Fixes: 81927e2808 ("drm/amd/display: Support for DMUB AUX")
Assisted-by: Copilot:claude-opus-4.8
Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: George Zhang <george.zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Harry Wentland
2026-07-01 11:34:29 -04:00
committed by Alex Deucher
parent f3403ab74a
commit 8cbe3648aa
1 changed files with 19 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_dmub.c
+19 -5
View File
@@ -797,12 +797,26 @@ int amdgpu_dm_process_dmub_aux_transfer_sync(
payload->reply[0] = (adev->dm.dmub_notify->aux_reply.command >> 4) & 0xF;
/*write req may receive a byte indicating partially written number as well*/
if (p_notify->aux_reply.length)
memcpy(payload->data, p_notify->aux_reply.data,
p_notify->aux_reply.length);
if (p_notify->aux_reply.length && payload->data) {
/* Bound the reply to the scratch buffer it was read into. */
ret = min((uint32_t)p_notify->aux_reply.length,
(uint32_t)sizeof(p_notify->aux_reply.data));
/*
* During a write-status-update retry the caller zeroes
* payload->length while still expecting the partial-write
* status byte in payload->data (see dce_aux_transfer_with_retries),
* so only clamp to payload->length for regular transfers.
*/
if (!payload->write_status_update)
ret = min(ret, payload->length);
memcpy(payload->data, p_notify->aux_reply.data, ret);
} else {
/* success */
ret = p_notify->aux_reply.length;
}
/* success */
ret = p_notify->aux_reply.length;
*operation_result = p_notify->result;
out:
reinit_completion(&adev->dm.dmub_aux_transfer_done);