From: Jose Fernandez josef@netflix.com

stable inclusion from stable-v5.15.160 commit a32c8f951c8a456c1c251e1dcdf21787f8066445 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IA3UT7 CVE: CVE-2024-36969

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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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@amd.com Signed-off-by: Jose Fernandez josef@netflix.com Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3113 Signed-off-by: Rodrigo Siqueira Rodrigo.Siqueira@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Cc: "Limonciello, Mario" mario.limonciello@amd.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

Conflicts: drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c [Context conflicts.] Signed-off-by: Jinjiang Tu tujinjiang@huawei.com --- drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c index 4c844cfaa956..cbbcc34ac58b 100644 --- a/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c +++ b/drivers/gpu/drm/amd/display/dc/dsc/dc_dsc.c @@ -735,7 +735,12 @@ 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; + }

// Final decission: can we do DSC or not? if (is_dsc_possible) {