Re: [PATCH] media: verisilicon: Final fix for the crash when opening the driver

[Nicolas Dufresne <nicolas@ndufresne.ca>]

Le vendredi 21 avril 2023 à 12:47 +0200, Marek Szyprowski a écrit :
> ctx->vpu_src_fmt is no more initialized before calling hantro_try_fmt()
> so checking it led to crash the kernel. Simply use the provided 'fmt' as
> a format for those checks.
> 
> This fixes the following issue observed on Odroid-M1 board:
> 
>  Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008
>  Mem abort info:
>  ...
>  Modules linked in: crct10dif_ce hantro_vpu snd_soc_simple_card snd_soc_simple_card_utils v4l2_vp9 v4l2_h264 rockchip_saradc v4l2_mem2mem videobuf2_dma_contig videobuf2_memops rtc_rk808 videobuf2_v4l2 industrialio_triggered_buffer rockchip_thermal dwmac_rk stmmac_platform stmmac videodev kfifo_buf display_connector videobuf2_common pcs_xpcs mc rockchipdrm analogix_dp dw_mipi_dsi dw_hdmi drm_display_helper panfrost drm_shmem_helper gpu_sched ip_tables x_tables ipv6
>  CPU: 3 PID: 176 Comm: v4l_id Not tainted 6.3.0-rc7-next-20230420 #13481
>  Hardware name: Hardkernel ODROID-M1 (DT)
>  pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>  pc : hantro_try_fmt+0xa0/0x278 [hantro_vpu]
>  lr : hantro_try_fmt+0x94/0x278 [hantro_vpu]
>  ...
>  Call trace:
>   hantro_try_fmt+0xa0/0x278 [hantro_vpu]
>   hantro_set_fmt_out+0x3c/0x298 [hantro_vpu]
>   hantro_reset_raw_fmt+0x98/0x128 [hantro_vpu]
>   hantro_set_fmt_cap+0x240/0x254 [hantro_vpu]
>   hantro_reset_encoded_fmt+0x94/0xcc [hantro_vpu]
>   hantro_reset_fmts+0x18/0x38 [hantro_vpu]
>   hantro_open+0xd4/0x20c [hantro_vpu]
>   v4l2_open+0x80/0x120 [videodev]
>   chrdev_open+0xc0/0x22c
>   do_dentry_open+0x13c/0x48c
>   vfs_open+0x2c/0x38
>   path_openat+0x550/0x934
>   do_filp_open+0x80/0x12c
>   do_sys_openat2+0xb4/0x168
>   __arm64_sys_openat+0x64/0xac
>   invoke_syscall+0x48/0x114
>   el0_svc_common+0x100/0x120
>   do_el0_svc+0x3c/0xa8
>   el0_svc+0x40/0xa8
>   el0t_64_sync_handler+0xb8/0xbc
>   el0t_64_sync+0x190/0x194
>  Code: 97fc8a7f f940aa80 52864a61 72a686c1 (b9400800) 
>  ---[ end trace 0000000000000000 ]---
> 
> Fixes: db6f68b51e5c ("media: verisilicon: Do not set context src/dst formats in reset functions")
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> ---
> It looks that I've missed the fact that the first fix merged as commit
> f100ce3bbd6a ("media: verisilicon: Fix crash when probing encoder") did
> not fix all the issues introduced by db6f68b51e5c ("media: verisilicon:
> Do not set context src/dst formats in reset functions"). I'm really sorry
> for that.
> ---
>  drivers/media/platform/verisilicon/hantro_v4l2.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/platform/verisilicon/hantro_v4l2.c b/drivers/media/platform/verisilicon/hantro_v4l2.c
> index 835518534e3b..618ea23a7d49 100644
> --- a/drivers/media/platform/verisilicon/hantro_v4l2.c
> +++ b/drivers/media/platform/verisilicon/hantro_v4l2.c
> @@ -313,17 +313,17 @@ static int hantro_try_fmt(const struct hantro_ctx *ctx,
>  		/* Fill remaining fields */
>  		v4l2_fill_pixfmt_mp(pix_mp, fmt->fourcc, pix_mp->width,
>  				    pix_mp->height);
> -		if (ctx->vpu_src_fmt->fourcc == V4L2_PIX_FMT_H264_SLICE &&
> +		if (fmt->fourcc == V4L2_PIX_FMT_H264_SLICE &&

In this context, we have !coded, so fmt->fourcc will never be any of H264, VP9
or HEVC, so we'llnever allocate space for motion vector. I'm surprise you are
getting anything working after that. What this code is trying to achieve is to
pad the size of raw images depending on the selected coded format (opposite
queue).

I think the proper fix is to actually fix the default coded format setup. This
will ensure that vpu_src_fmt is always valid. The same pointer can be used in
start-streaming it seems.

>  		    !hantro_needs_postproc(ctx, fmt))
>  			pix_mp->plane_fmt[0].sizeimage +=
>  				hantro_h264_mv_size(pix_mp->width,
>  						    pix_mp->height);
> -		else if (ctx->vpu_src_fmt->fourcc == V4L2_PIX_FMT_VP9_FRAME &&
> +		else if (fmt->fourcc == V4L2_PIX_FMT_VP9_FRAME &&
>  			 !hantro_needs_postproc(ctx, fmt))
>  			pix_mp->plane_fmt[0].sizeimage +=
>  				hantro_vp9_mv_size(pix_mp->width,
>  						   pix_mp->height);
> -		else if (ctx->vpu_src_fmt->fourcc == V4L2_PIX_FMT_HEVC_SLICE &&
> +		else if (fmt->fourcc == V4L2_PIX_FMT_HEVC_SLICE &&
>  			 !hantro_needs_postproc(ctx, fmt))
>  			pix_mp->plane_fmt[0].sizeimage +=
>  				hantro_hevc_mv_size(pix_mp->width,


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