[PATCH] phy: sunplus: fix crash when the disc_vol nvmem cell is missing

[PATCH] phy: sunplus: fix crash when the disc_vol nvmem cell is missing

[Felix Gu]

nvmem_cell_get() can fail with errors other than -EPROBE_DEFER, but
update_disc_vol() only handled -EPROBE_DEFER and then called
nvmem_cell_read() with the error pointer, crashing the kernel.

Fall back to the default disconnect voltage on a failed cell lookup,
and free the buffer returned by nvmem_cell_read().

Fixes: 99d9ccd97385 ("phy: usb: Add USB2.0 phy driver for Sunplus SP7021")
Signed-off-by: Felix Gu <ustc.gu@gmail.com>
---
 drivers/phy/sunplus/phy-sunplus-usb2.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/phy/sunplus/phy-sunplus-usb2.c b/drivers/phy/sunplus/phy-sunplus-usb2.c
index 637a5fbae6d9..94146118e9c2 100644
--- a/drivers/phy/sunplus/phy-sunplus-usb2.c
+++ b/drivers/phy/sunplus/phy-sunplus-usb2.c
@@ -81,12 +81,13 @@ static int update_disc_vol(struct sp_usbphy *usbphy)
 	char *disc_name = "disc_vol";
 	ssize_t otp_l = 0;
 	char *otp_v;
-	u32 val, set;
+	u32 val, set = OTP_DISC_LEVEL_DEFAULT;
 
 	cell = nvmem_cell_get(usbphy->dev, disc_name);
-	if (IS_ERR_OR_NULL(cell)) {
+	if (IS_ERR(cell)) {
 		if (PTR_ERR(cell) == -EPROBE_DEFER)
 			return -EPROBE_DEFER;
+		goto out;
 	}
 
 	otp_v = nvmem_cell_read(cell, &otp_l);
@@ -96,11 +97,12 @@ static int update_disc_vol(struct sp_usbphy *usbphy)
 		set = *(otp_v + 1);
 		set = (set << (sizeof(char) * 8)) | *otp_v;
 		set = (set >> usbphy->disc_vol_addr_off) & J_DISC;
+		if (set == 0)
+			set = OTP_DISC_LEVEL_DEFAULT;
+		kfree(otp_v);
 	}
 
-	if (IS_ERR(otp_v) || set == 0)
-		set = OTP_DISC_LEVEL_DEFAULT;
-
+out:
 	val = readl(usbphy->phy_regs + CONFIG7);
 	val = (val & ~J_DISC) | set;
 	writel(val, usbphy->phy_regs + CONFIG7);

---
base-commit: 9a4cdc958dd79fc6c3b20b51a10debec6ca09fec
change-id: 20260804-sunplus-53a7bb1bcd72

Best regards,
--  
Felix Gu <ustc.gu@gmail.com>

Re: [PATCH] phy: sunplus: fix crash when the disc_vol nvmem cell is missing

[Vinod Koul]

On 04-08-26, 21:58, Felix Gu wrote:

Where is the crash report?
Patch title should document the change not the reason, please read the
documentation on how to create patches

> nvmem_cell_get() can fail with errors other than -EPROBE_DEFER, but
> update_disc_vol() only handled -EPROBE_DEFER and then called
> nvmem_cell_read() with the error pointer, crashing the kernel.
> 
> Fall back to the default disconnect voltage on a failed cell lookup,
> and free the buffer returned by nvmem_cell_read().
> 
> Fixes: 99d9ccd97385 ("phy: usb: Add USB2.0 phy driver for Sunplus SP7021")
> Signed-off-by: Felix Gu <ustc.gu@gmail.com>
> ---
>  drivers/phy/sunplus/phy-sunplus-usb2.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/phy/sunplus/phy-sunplus-usb2.c b/drivers/phy/sunplus/phy-sunplus-usb2.c
> index 637a5fbae6d9..94146118e9c2 100644
> --- a/drivers/phy/sunplus/phy-sunplus-usb2.c
> +++ b/drivers/phy/sunplus/phy-sunplus-usb2.c
> @@ -81,12 +81,13 @@ static int update_disc_vol(struct sp_usbphy *usbphy)
>  	char *disc_name = "disc_vol";
>  	ssize_t otp_l = 0;
>  	char *otp_v;
> -	u32 val, set;
> +	u32 val, set = OTP_DISC_LEVEL_DEFAULT;
>  
>  	cell = nvmem_cell_get(usbphy->dev, disc_name);
> -	if (IS_ERR_OR_NULL(cell)) {
> +	if (IS_ERR(cell)) {
>  		if (PTR_ERR(cell) == -EPROBE_DEFER)
>  			return -EPROBE_DEFER;
> +		goto out;
>  	}
>  
>  	otp_v = nvmem_cell_read(cell, &otp_l);
> @@ -96,11 +97,12 @@ static int update_disc_vol(struct sp_usbphy *usbphy)
>  		set = *(otp_v + 1);
>  		set = (set << (sizeof(char) * 8)) | *otp_v;
>  		set = (set >> usbphy->disc_vol_addr_off) & J_DISC;
> +		if (set == 0)
> +			set = OTP_DISC_LEVEL_DEFAULT;
> +		kfree(otp_v);
>  	}
>  
> -	if (IS_ERR(otp_v) || set == 0)
> -		set = OTP_DISC_LEVEL_DEFAULT;
> -
> +out:
>  	val = readl(usbphy->phy_regs + CONFIG7);
>  	val = (val & ~J_DISC) | set;
>  	writel(val, usbphy->phy_regs + CONFIG7);
> 
> ---
> base-commit: 9a4cdc958dd79fc6c3b20b51a10debec6ca09fec
> change-id: 20260804-sunplus-53a7bb1bcd72
> 
> Best regards,
> --  
> Felix Gu <ustc.gu@gmail.com>

-- 
~Vinod