This is a note to let you know that I've just added the patch titled
drm/amd/display: Fix division by zero in setup_dsc_config
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-amd-display-fix-division-by-zero-in-setup_dsc_config.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 130afc8a886183a94cf6eab7d24f300014ff87ba Mon Sep 17 00:00:00 2001
From: Jose Fernandez <josef@xxxxxxxxxxx>
Date: Mon, 22 Apr 2024 08:35:44 -0600
Subject: drm/amd/display: Fix division by zero in setup_dsc_config
From: Jose Fernandez <josef@xxxxxxxxxxx>
commit 130afc8a886183a94cf6eab7d24f300014ff87ba upstream.
When slice_height is 0, the division by slice_height in the calculation
of the number of slices will cause a division by zero driver crash. This
leaves the kernel in a state that requires a reboot. This patch adds a
check to avoid the division by zero.
The stack trace below is for the 6.8.4 Kernel. I reproduced the issue on
a Z16 Gen 2 Lenovo Thinkpad with a Apple Studio Display monitor
connected via Thunderbolt. The amdgpu driver crashed with this exception
when I rebooted the system with the monitor connected.
kernel: ? die (arch/x86/kernel/dumpstack.c:421 arch/x86/kernel/dumpstack.c:434 arch/x86/kernel/dumpstack.c:447)
kernel: ? do_trap (arch/x86/kernel/traps.c:113 arch/x86/kernel/traps.c:154)
kernel: ? setup_dsc_config (drivers/gpu/drm/amd/amdgpu/../display/dc/dsc/dc_dsc.c:1053) amdgpu
kernel: ? do_error_trap (./arch/x86/include/asm/traps.h:58 arch/x86/kernel/traps.c:175)
kernel: ? setup_dsc_config (drivers/gpu/drm/amd/amdgpu/../display/dc/dsc/dc_dsc.c:1053) amdgpu
kernel: ? exc_divide_error (arch/x86/kernel/traps.c:194 (discriminator 2))
kernel: ? setup_dsc_config (drivers/gpu/drm/amd/amdgpu/../display/dc/dsc/dc_dsc.c:1053) amdgpu
kernel: ? asm_exc_divide_error (./arch/x86/include/asm/idtentry.h:548)
kernel: ? setup_dsc_config (drivers/gpu/drm/amd/amdgpu/../display/dc/dsc/dc_dsc.c:1053) amdgpu
kernel: dc_dsc_compute_config (drivers/gpu/drm/amd/amdgpu/../display/dc/dsc/dc_dsc.c:1109) amdgpu
After applying this patch, the driver no longer crashes when the monitor
is connected and the system is rebooted. I believe this is the same
issue reported for 3113.
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@xxxxxxx>
Signed-off-by: Jose Fernandez <josef@xxxxxxxxxxx>
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3113
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: "Limonciello, Mario" <mario.limonciello@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
--- a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
+++ b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c
@@ -939,7 +939,12 @@ static bool setup_dsc_config(
if (!is_dsc_possible)
goto done;
- dsc_cfg->num_slices_v = pic_height/slice_height;
+ if (slice_height > 0) {
+ dsc_cfg->num_slices_v = pic_height / slice_height;
+ } else {
+ is_dsc_possible = false;
+ goto done;
+ }
if (target_bandwidth_kbps > 0) {
is_dsc_possible = decide_dsc_target_bpp_x16(
Patches currently in stable-queue which might be from josef@xxxxxxxxxxx are
queue-5.15/drm-amd-display-fix-division-by-zero-in-setup_dsc_config.patch
