Re: [PATCH] media: rkvdec: Handle interrupts without a current context

[Nicolas Dufresne]

Hi,

Le vendredi 23 octobre 2026 à 17:11 +0400, Alex Kazinsky a écrit :
> The watchdog can finish the current job before the threaded IRQ handler
> retrieves its context. In that case, v4l2_m2m_get_curr_priv() returns NULL,
> but the variant IRQ handlers unconditionally dereference ctx->dev.
> 
> Pass the device pointer to the variant IRQ handlers independently of the
> context. Clear the interrupt status and, for VDPU383, disable interrupts
> before returning if no current context exists. This avoids dereferencing
> NULL while still acknowledging the interrupt.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.

Can you share you proof of concept please. Can be private if you plane to
produce a CVE report.

Nicolas

> 
> Fixes: f9c7b7deeffd ("media: rkvdec: Support per-variant interrupt handler")
> Signed-off-by: Alex Kazinsky <a.kazinsky@xxxxxxxx>
> ---
>  .../media/platform/rockchip/rkvdec/rkvdec.c   | 23 +++++++++++++------
>  .../media/platform/rockchip/rkvdec/rkvdec.h   |  4 +++-
>  2 files changed, 19 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/media/platform/rockchip/rkvdec/rkvdec.c b/drivers/media/platform/rockchip/rkvdec/rkvdec.c
> index 061281f903f3..02f6a574a8eb 100644
> --- a/drivers/media/platform/rockchip/rkvdec/rkvdec.c
> +++ b/drivers/media/platform/rockchip/rkvdec/rkvdec.c
> @@ -1434,15 +1434,18 @@ static void rkvdec_iommu_restore(struct rkvdec_dev *rkvdec)
>  	}
>  }
>  
> -static irqreturn_t rk3399_irq_handler(struct rkvdec_ctx *ctx)
> +static irqreturn_t rk3399_irq_handler(struct rkvdec_dev *rkvdec,
> +				    struct rkvdec_ctx *ctx)
>  {
> -	struct rkvdec_dev *rkvdec = ctx->dev;
>  	enum vb2_buffer_state state;
>  	u32 status;
>  
>  	status = readl(rkvdec->regs + RKVDEC_REG_INTERRUPT);
>  	writel(0, rkvdec->regs + RKVDEC_REG_INTERRUPT);
>  
> +	if (!ctx)
> +		return IRQ_HANDLED;
> +
>  	if (status & RKVDEC_RDY_STA) {
>  		state = VB2_BUF_STATE_DONE;
>  	} else {
> @@ -1457,9 +1460,9 @@ static irqreturn_t rk3399_irq_handler(struct rkvdec_ctx *ctx)
>  	return IRQ_HANDLED;
>  }
>  
> -static irqreturn_t vdpu381_irq_handler(struct rkvdec_ctx *ctx)
> +static irqreturn_t vdpu381_irq_handler(struct rkvdec_dev *rkvdec,
> +				    struct rkvdec_ctx *ctx)
>  {
> -	struct rkvdec_dev *rkvdec = ctx->dev;
>  	enum vb2_buffer_state state;
>  	bool need_reset = 0;
>  	u32 status;
> @@ -1467,6 +1470,9 @@ static irqreturn_t vdpu381_irq_handler(struct rkvdec_ctx *ctx)
>  	status = readl(rkvdec->regs + VDPU381_REG_STA_INT);
>  	writel(0, rkvdec->regs + VDPU381_REG_STA_INT);
>  
> +	if (!ctx)
> +		return IRQ_HANDLED;
> +
>  	if (status & VDPU381_STA_INT_DEC_RDY_STA) {
>  		state = VB2_BUF_STATE_DONE;
>  	} else {
> @@ -1486,9 +1492,9 @@ static irqreturn_t vdpu381_irq_handler(struct rkvdec_ctx *ctx)
>  	return IRQ_HANDLED;
>  }
>  
> -static irqreturn_t vdpu383_irq_handler(struct rkvdec_ctx *ctx)
> +static irqreturn_t vdpu383_irq_handler(struct rkvdec_dev *rkvdec,
> +				    struct rkvdec_ctx *ctx)
>  {
> -	struct rkvdec_dev *rkvdec = ctx->dev;
>  	enum vb2_buffer_state state;
>  	bool need_reset = 0;
>  	u32 status;
> @@ -1499,6 +1505,9 @@ static irqreturn_t vdpu383_irq_handler(struct rkvdec_ctx *ctx)
>  	writel(FIELD_PREP_WM16(VDPU383_INT_EN_IRQ | VDPU383_INT_EN_LINE_IRQ, 0),
>  	       rkvdec->link + VDPU383_LINK_INT_EN);
>  
> +	if (!ctx)
> +		return IRQ_HANDLED;
> +
>  	if (status & VDPU383_STA_INT_DEC_RDY_STA) {
>  		state = VB2_BUF_STATE_DONE;
>  	} else {
> @@ -1521,7 +1530,7 @@ static irqreturn_t rkvdec_irq_handler(int irq, void *priv)
>  	struct rkvdec_ctx *ctx = v4l2_m2m_get_curr_priv(rkvdec->m2m_dev);
>  	const struct rkvdec_variant *variant = rkvdec->variant;
>  
> -	return variant->ops->irq_handler(ctx);
> +	return variant->ops->irq_handler(rkvdec, ctx);
>  }
>  
>  /*
> diff --git a/drivers/media/platform/rockchip/rkvdec/rkvdec.h b/drivers/media/platform/rockchip/rkvdec/rkvdec.h
> index a24be6638b6b..2e03ff6e33d7 100644
> --- a/drivers/media/platform/rockchip/rkvdec/rkvdec.h
> +++ b/drivers/media/platform/rockchip/rkvdec/rkvdec.h
> @@ -30,6 +30,7 @@
>  #define RKVDEC_8K_PIXELS		(7680 * 4320)
>  
>  struct rkvdec_ctx;
> +struct rkvdec_dev;
>  struct rkvdec_rcb_config;
>  
>  struct rkvdec_ctrl_desc {
> @@ -72,7 +73,8 @@ vb2_to_rkvdec_decoded_buf(struct vb2_buffer *buf)
>  }
>  
>  struct rkvdec_variant_ops {
> -	irqreturn_t (*irq_handler)(struct rkvdec_ctx *ctx);
> +	irqreturn_t (*irq_handler)(struct rkvdec_dev *rkvdec,
> +			   struct rkvdec_ctx *ctx);
>  	u32 (*colmv_size)(u16 width, u16 height);
>  	void (*flatten_matrices)(u8 *output, const u8 *input, int matrices, int row_length);
>  };

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