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Message-ID: <e7d57472-08f9-4e71-8c42-2f95d9a81f75@collabora.com>
Date: Wed, 28 Feb 2024 11:09:23 +0100
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Nicolas Dufresne <nicolas.dufresne@...labora.com>,
Tiffany Lin <tiffany.lin@...iatek.com>,
Andrew-CT Chen <andrew-ct.chen@...iatek.com>,
Yunfei Dong <yunfei.dong@...iatek.com>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Matthias Brugger <matthias.bgg@...il.com>,
Hans Verkuil <hverkuil-cisco@...all.nl>
Cc: kernel@...labora.com, linux-media@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH] media: mediatek: vcodec: Fix oops when HEVC init fails
Il 26/02/24 22:19, Nicolas Dufresne ha scritto:
> In stateless HEVC case, the instance pointer was saved in the
> context regardless if the initialization worked. As the pointer
> is freed in failure, this resulted in use after free in the
> deinit function.
>
From what I understand, "the pointer" that is freed is struct vdec_vpu_inst; is
that correct?
Since you do have a way to easily reproduce the issue on your side, can we resolve
the safety/reliability root issue as well as making this correct?
The idea is being able to avoid a kernel panic in the situation that you describe
in this fix, but throw an error message (read: throw a big "wtf!") when this does
happen, and handle that with returning an error code (avoiding a kernel crash).
Let's cut it short - please try this:
In functions
- int vpu_vdec_start()
- int vpu_dec_get_param()
- int vcodec_send_ap_ipi()
at the beginning, perform this check:
if (unlikely(!vpu)) {
/* Write a scarier message if this is not scary enough */
mtk_vdec_err("FIXME!! - VPU is NULL. This is unexpected.\n");
return -EINVAL; /* or something else if more meaningful */
}
Unless I've misunderstood what's NULL, that'll work. :-)
Meanwhile, for this fix:
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cheers,
Angelo
> Hardware name: Acer Tomato (rev3 - 4) board (DT)
> pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : vcodec_vpu_send_msg+0x4c/0x190 [mtk_vcodec_dec]
> lr : vcodec_send_ap_ipi+0x78/0x170 [mtk_vcodec_dec]
> sp : ffff80008750bc20
> x29: ffff80008750bc20 x28: ffff1299f6d70000 x27: 0000000000000000
> x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000
> x23: ffff80008750bc98 x22: 000000000000a003 x21: ffffd45c4cfae000
> x20: 0000000000000010 x19: ffff1299fd668310 x18: 000000000000001a
> x17: 000000040044ffff x16: ffffd45cb15dc648 x15: 0000000000000000
> x14: ffff1299c08da1c0 x13: ffffd45cb1f87a10 x12: ffffd45cb2f5fe80
> x11: 0000000000000001 x10: 0000000000001b30 x9 : ffffd45c4d12b488
> x8 : 1fffe25339380d81 x7 : 0000000000000001 x6 : ffff1299c9c06c00
> x5 : 0000000000000132 x4 : 0000000000000000 x3 : 0000000000000000
> x2 : 0000000000000010 x1 : ffff80008750bc98 x0 : 0000000000000000
> Call trace:
> vcodec_vpu_send_msg+0x4c/0x190 [mtk_vcodec_dec]
> vcodec_send_ap_ipi+0x78/0x170 [mtk_vcodec_dec]
> vpu_dec_deinit+0x1c/0x30 [mtk_vcodec_dec]
> vdec_hevc_slice_deinit+0x30/0x98 [mtk_vcodec_dec]
> vdec_if_deinit+0x38/0x68 [mtk_vcodec_dec]
> mtk_vcodec_dec_release+0x20/0x40 [mtk_vcodec_dec]
> fops_vcodec_release+0x64/0x118 [mtk_vcodec_dec]
> v4l2_release+0x7c/0x100
> __fput+0x80/0x2d8
> __fput_sync+0x58/0x70
> __arm64_sys_close+0x40/0x90
> invoke_syscall+0x50/0x128
> el0_svc_common.constprop.0+0x48/0xf0
> do_el0_svc+0x24/0x38
> el0_svc+0x38/0xd8
> el0t_64_sync_handler+0xc0/0xc8
> el0t_64_sync+0x1a8/0x1b0
> Code: d503201f f9401660 b900127f b900227f (f9400400)
>
> Signed-off-by: Nicolas Dufresne <nicolas.dufresne@...labora.com>
> Fixes: 2674486aac7d ("media: mediatek: vcodec: support stateless hevc decoder")
> ---
> .../mediatek/vcodec/decoder/vdec/vdec_hevc_req_multi_if.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/mediatek/vcodec/decoder/vdec/vdec_hevc_req_multi_if.c b/drivers/media/platform/mediatek/vcodec/decoder/vdec/vdec_hevc_req_multi_if.c
> index 06ed47df693bf..21836dd6ef85a 100644
> --- a/drivers/media/platform/mediatek/vcodec/decoder/vdec/vdec_hevc_req_multi_if.c
> +++ b/drivers/media/platform/mediatek/vcodec/decoder/vdec/vdec_hevc_req_multi_if.c
> @@ -869,7 +869,6 @@ static int vdec_hevc_slice_init(struct mtk_vcodec_dec_ctx *ctx)
> inst->vpu.codec_type = ctx->current_codec;
> inst->vpu.capture_type = ctx->capture_fourcc;
>
> - ctx->drv_handle = inst;
> err = vpu_dec_init(&inst->vpu);
> if (err) {
> mtk_vdec_err(ctx, "vdec_hevc init err=%d", err);
> @@ -898,6 +897,7 @@ static int vdec_hevc_slice_init(struct mtk_vcodec_dec_ctx *ctx)
> mtk_vdec_debug(ctx, "lat hevc instance >> %p, codec_type = 0x%x",
> inst, inst->vpu.codec_type);
>
> + ctx->drv_handle = inst;
> return 0;
> error_free_inst:
> kfree(inst);
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