[PATCH][next] soc: fsl: dpio: fix dereference of pointer p before null check

[PATCH][next] soc: fsl: dpio: fix dereference of pointer p before null check

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

Pointer p is currently being dereferenced before it is null
checked on a memory allocation failure check. Fix this by
checking if p is null before dereferencing it.

Addresses-Coverity: ("Dereference before null check")
Fixes: 3b2abda7d28c ("soc: fsl: dpio: Replace QMAN array mode with ring mode enqueue")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/soc/fsl/dpio/qbman-portal.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/fsl/dpio/qbman-portal.c b/drivers/soc/fsl/dpio/qbman-portal.c
index 740ee0d19582..d1f49caa5b13 100644
--- a/drivers/soc/fsl/dpio/qbman-portal.c
+++ b/drivers/soc/fsl/dpio/qbman-portal.c
@@ -249,10 +249,11 @@ struct qbman_swp *qbman_swp_init(const struct qbman_swp_desc *d)
 	u32 mask_size;
 	u32 eqcr_pi;
 
-	spin_lock_init(&p->access_spinlock);
-
 	if (!p)
 		return NULL;
+
+	spin_lock_init(&p->access_spinlock);
+
 	p->desc = d;
 	p->mc.valid_bit = QB_VALID_BIT;
 	p->sdq = 0;
-- 
2.25.0

RE: [PATCH][next] soc: fsl: dpio: fix dereference of pointer p before null check

[Leo Li]

> -----Original Message-----
> From: Colin King <colin.king@canonical.com>
> Sent: Friday, February 21, 2020 5:12 PM
> To: Roy Pledge <roy.pledge@nxp.com>; Leo Li <leoyang.li@nxp.com>; Youri
> Querry <youri.querry_1@nxp.com>; linuxppc-dev@lists.ozlabs.org; linux-
> arm-kernel@lists.infradead.org
> Cc: kernel-janitors@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: [PATCH][next] soc: fsl: dpio: fix dereference of pointer p before null
> check
> 
> From: Colin Ian King <colin.king@canonical.com>
> 
> Pointer p is currently being dereferenced before it is null checked on a
> memory allocation failure check. Fix this by checking if p is null before
> dereferencing it.
> 
> Addresses-Coverity: ("Dereference before null check")
> Fixes: 3b2abda7d28c ("soc: fsl: dpio: Replace QMAN array mode with ring
> mode enqueue")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

Applied for next.  Thanks.

> ---
>  drivers/soc/fsl/dpio/qbman-portal.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/soc/fsl/dpio/qbman-portal.c
> b/drivers/soc/fsl/dpio/qbman-portal.c
> index 740ee0d19582..d1f49caa5b13 100644
> --- a/drivers/soc/fsl/dpio/qbman-portal.c
> +++ b/drivers/soc/fsl/dpio/qbman-portal.c
> @@ -249,10 +249,11 @@ struct qbman_swp *qbman_swp_init(const struct
> qbman_swp_desc *d)
>  	u32 mask_size;
>  	u32 eqcr_pi;
> 
> -	spin_lock_init(&p->access_spinlock);
> -
>  	if (!p)
>  		return NULL;
> +
> +	spin_lock_init(&p->access_spinlock);
> +
>  	p->desc = d;
>  	p->mc.valid_bit = QB_VALID_BIT;
>  	p->sdq = 0;
> --
> 2.25.0

Re: [PATCH][next] soc: fsl: dpio: fix dereference of pointer p before null check

[Dan Carpenter]

On Fri, Feb 21, 2020 at 11:11:43PM +0000, Colin King wrote:
> ---
>  drivers/soc/fsl/dpio/qbman-portal.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/soc/fsl/dpio/qbman-portal.c b/drivers/soc/fsl/dpio/qbman-portal.c
> index 740ee0d19582..d1f49caa5b13 100644
> --- a/drivers/soc/fsl/dpio/qbman-portal.c
> +++ b/drivers/soc/fsl/dpio/qbman-portal.c
> @@ -249,10 +249,11 @@ struct qbman_swp *qbman_swp_init(const struct qbman_swp_desc *d)
>  	u32 mask_size;
>  	u32 eqcr_pi;
>  
> -	spin_lock_init(&p->access_spinlock);
> -
>  	if (!p)
>  		return NULL;
> +
> +	spin_lock_init(&p->access_spinlock);

Allocations in the declaration blog are not super common in the kernel,
but they're more bug prone.  Generally, it's not beautiful to call a
function which can fail in the allocation block.

regards,
dan carpenter