On 2020-09-02 03:29, Stephen Boyd wrote:
The cstate->num_mixers member is only set to a non-zero value once
dpu_encoder_virt_mode_set() is called, but the atomic check function
can
be called by userspace before that. Let's avoid the div-by-zero here
and
inside _dpu_crtc_setup_lm_bounds() by skipping this part of the atomic
check if dpu_encoder_virt_mode_set() hasn't been called yet. This fixes
an UBSAN warning:
UBSAN: Undefined behaviour in
drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c:860:31
division by zero
CPU: 7 PID: 409 Comm: frecon Tainted: G S 5.4.31 #128
Hardware name: Google Trogdor (rev0) (DT)
Call trace:
dump_backtrace+0x0/0x14c
show_stack+0x20/0x2c
dump_stack+0xa0/0xd8
__ubsan_handle_divrem_overflow+0xec/0x110
dpu_crtc_atomic_check+0x97c/0x9d4
drm_atomic_helper_check_planes+0x160/0x1c8
drm_atomic_helper_check+0x54/0xbc
drm_atomic_check_only+0x6a8/0x880
drm_atomic_commit+0x20/0x5c
drm_atomic_helper_set_config+0x98/0xa0
drm_mode_setcrtc+0x308/0x5dc
drm_ioctl_kernel+0x9c/0x114
drm_ioctl+0x2ac/0x4b0
drm_compat_ioctl+0xe8/0x13c
__arm64_compat_sys_ioctl+0x184/0x324
el0_svc_common+0xa4/0x154
el0_svc_compat_handler+0x
Cc: Abhinav Kumar <abhinavk@xxxxxxxxxxxxxx>
Cc: Jeykumar Sankaran <jsanka@xxxxxxxxxxxxxx>
Cc: Jordan Crouse <jcrouse@xxxxxxxxxxxxxx>
Cc: Sean Paul <seanpaul@xxxxxxxxxxxx>
Fixes: 25fdd5933e4c ("drm/msm: Add SDM845 DPU support")
Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
---
Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
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