Re: [PATCH] media: chips-media: wave5: fix panic on decoding DECODED_IDX_FLAG_SKIP

[Sebastian Fricke]

Hello Mattijs,

Thanks for the patch!

On 29.11.2023 11:37, Mattijs Korpershoek wrote:
> The display frame region information received from the vpu also
> contains the frame display index: info->index_frame_display.
>
> This index, being a s32, can be negative when a skip option is passed.
> In that case, its value is DECODED_IDX_FLAG_SKIP (-2).
>
> When disp_idx == -2, the following exception occurs:

Could you please highlight how you were able to produce this error? For
example by providing the file you decoded in combination with the
command that you used. (Please also provide the version of userspace you use)

Greetings,
Sebastian

> [ 1530.782246][ T1900] Hardware name: Texas Instruments AM62P5 SK (DT)
> [ 1530.788501][ T1900] pstate: a0400005 (NzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [ 1530.796144][ T1900] pc : wave5_vpu_dec_get_output_info+0x300/0x308 [wave5]
> [ 1530.803060][ T1900] lr : wave5_vpu_dec_get_output_info+0x80/0x308 [wave5]
> [ 1530.809873][ T1900] sp : ffffffc00b85bc00
> [ 1530.813872][ T1900] x29: ffffffc00b85bc00 x28: 0000000000000000 x27: 0000000000000001
> [ 1530.821695][ T1900] x26: 00000000fffffffd x25: 00000000ffffffff x24: ffffff8812820000
> [ 1530.829516][ T1900] x23: ffffff88199f7840 x22: ffffff8873f5e000 x21: ffffffc00b85bc58
> [ 1530.837336][ T1900] x20: 0000000000000000 x19: ffffff88199f7920 x18: ffffffc00a899030
> [ 1530.845156][ T1900] x17: 00000000529c6ef0 x16: 00000000529c6ef0 x15: 0000000000198487
> [ 1530.852975][ T1900] x14: ffffffc009f2b650 x13: 0000000000058016 x12: 0000000005000000
> [ 1530.860795][ T1900] x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000
> [ 1530.868615][ T1900] x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000004086
> [ 1530.876434][ T1900] x5 : 0000000000000001 x4 : ffffffc001454b94 x3 : ffffffc001454d94
> [ 1530.884256][ T1900] x2 : ffffffc00b8201d0 x1 : 0000000000000020 x0 : 0000000000000000
> [ 1530.892087][ T1900] Call trace:
> [ 1530.895225][ T1900]  wave5_vpu_dec_get_output_info+0x300/0x308 [wave5]
> [ 1530.901788][ T1900]  wave5_vpu_dec_finish_decode+0x6c/0x3dc [wave5]
> [ 1530.908081][ T1900]  wave5_vpu_irq_thread+0x140/0x168 [wave5]
> [ 1530.913856][ T1900]  irq_thread_fn+0x44/0xa4
> [ 1530.918154][ T1900]  irq_thread+0x15c/0x288
> [ 1530.922330][ T1900]  kthread+0x104/0x1d4
> [ 1530.926247][ T1900]  ret_from_fork+0x10/0x20
> [ 1530.930520][ T1900] Code: 2a1f03ea 2a1f03eb 35ffef2c 17ffff74 (d42aa240)
> [ 1530.937296][ T1900] ---[ end trace 0000000000000000 ]---
> [ 1530.942596][ T1900] Kernel panic - not syncing: BRK handler: Fatal exception
> [ 1530.949629][ T1900] SMP: stopping secondary CPUs
> [ 1530.954244][ T1900] Kernel Offset: disabled
> [ 1530.958415][ T1900] CPU features: 0x00,00000000,00800184,0000421b
> [ 1530.964496][ T1900] Memory Limit: none
>
> Move the disp_info assignment after testing that the index is positive
> to avoid the exception.
>
> Fixes: 45d1a2b93277 ("media: chips-media: wave5: Add vpuapi layer")
> Signed-off-by: Mattijs Korpershoek <mkorpershoek@xxxxxxxxxxxx>
> ---
> drivers/media/platform/chips-media/wave5/wave5-vpuapi.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/chips-media/wave5/wave5-vpuapi.c b/drivers/media/platform/chips-media/wave5/wave5-vpuapi.c
> index 86b3993722db..1a3efb638dde 100644
> --- a/drivers/media/platform/chips-media/wave5/wave5-vpuapi.c
> +++ b/drivers/media/platform/chips-media/wave5/wave5-vpuapi.c
> @@ -508,8 +508,8 @@ int wave5_vpu_dec_get_output_info(struct vpu_instance *inst, struct dec_output_i
> 	info->rc_decoded = rect_info;
>
> 	disp_idx = info->index_frame_display;
> -	disp_info = &p_dec_info->dec_out_info[disp_idx];
> 	if (info->index_frame_display >= 0 && info->index_frame_display < WAVE5_MAX_FBS) {
> +		disp_info = &p_dec_info->dec_out_info[disp_idx];
> 		if (info->index_frame_display != info->index_frame_decoded) {
> 			/*
> 			 * when index_frame_decoded < 0, and index_frame_display >= 0
>
> ---
> base-commit: a00b3f296eac3d43328615c3113e1a74143fc67a
> change-id: 20231129-wave5-panic-82ea2d30042f
>
> Best regards,
> --
> Mattijs Korpershoek <mkorpershoek@xxxxxxxxxxxx>