2020-03-06 13:05:21

by Benoit Parrot

Subject: [Patch v2] media: ti-vpe: cal: fix a kernel oops when unloading module

After the switch to use v4l2_async_notifier_add_subdev() and
v4l2_async_notifier_cleanup(), unloading the ti_cal module would casue a
kernel oops.

This was root cause to the fact that v4l2_async_notifier_cleanup() tries
to kfree the asd pointer passed into v4l2_async_notifier_add_subdev().

In our case the asd reference was from a statically allocated struct.
So in effect v4l2_async_notifier_cleanup() was trying to free a pointer
that was not kalloc.

So here we switch to using a kzalloc struct instead of a static one.
To acheive this we re-order some of the calls to prevent asd allocation
from leaking.

Fixes: d079f94c9046 ("media: platform: Switch to v4l2_async_notifier_add_subdev")

Cc: [email protected]
Signed-off-by: Benoit Parrot <[email protected]>
---
Changes since v1:
- fix asd allocation leak

drivers/media/platform/ti-vpe/cal.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/media/platform/ti-vpe/cal.c b/drivers/media/platform/ti-vpe/cal.c
index 6d4cbb8782ed..6c8f3702eac0 100644
--- a/drivers/media/platform/ti-vpe/cal.c
+++ b/drivers/media/platform/ti-vpe/cal.c
@@ -372,8 +372,6 @@ struct cal_ctx {
struct v4l2_subdev *sensor;
struct v4l2_fwnode_endpoint endpoint;

- struct v4l2_async_subdev asd;
-
struct v4l2_fh fh;
struct cal_dev *dev;
struct cc_data *cc;
@@ -2032,7 +2030,6 @@ static int of_cal_create_instance(struct cal_ctx *ctx, int inst)

parent = pdev->dev.of_node;

- asd = &ctx->asd;
endpoint = &ctx->endpoint;

ep_node = NULL;
@@ -2079,8 +2076,6 @@ static int of_cal_create_instance(struct cal_ctx *ctx, int inst)
ctx_dbg(3, ctx, "can't get remote parent\n");
goto cleanup_exit;
}
- asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
- asd->match.fwnode = of_fwnode_handle(sensor_node);

v4l2_fwnode_endpoint_parse(of_fwnode_handle(ep_node), endpoint);

@@ -2110,9 +2105,17 @@ static int of_cal_create_instance(struct cal_ctx *ctx, int inst)

v4l2_async_notifier_init(&ctx->notifier);

+ asd = kzalloc(sizeof(*asd), GFP_KERNEL);
+ if (!asd)
+ goto cleanup_exit;
+
+ asd->match_type = V4L2_ASYNC_MATCH_FWNODE;
+ asd->match.fwnode = of_fwnode_handle(sensor_node);
+
ret = v4l2_async_notifier_add_subdev(&ctx->notifier, asd);
if (ret) {
ctx_err(ctx, "Error adding asd\n");
+ kfree(asd);
goto cleanup_exit;
}

--
2.17.1

2020-03-10 08:56:46

by Tomi Valkeinen

Subject: Re: [Patch v2] media: ti-vpe: cal: fix a kernel oops when unloading module

On 06/03/2020 15:08, Benoit Parrot wrote:
> After the switch to use v4l2_async_notifier_add_subdev() and
> v4l2_async_notifier_cleanup(), unloading the ti_cal module would casue a
> kernel oops.
>
> This was root cause to the fact that v4l2_async_notifier_cleanup() tries
> to kfree the asd pointer passed into v4l2_async_notifier_add_subdev().
>
> In our case the asd reference was from a statically allocated struct.
> So in effect v4l2_async_notifier_cleanup() was trying to free a pointer
> that was not kalloc.
>
> So here we switch to using a kzalloc struct instead of a static one.
> To acheive this we re-order some of the calls to prevent asd allocation
> from leaking.
>
> Fixes: d079f94c9046 ("media: platform: Switch to v4l2_async_notifier_add_subdev")
>
> Cc: [email protected]
> Signed-off-by: Benoit Parrot <[email protected]>
> ---
> Changes since v1:
> - fix asd allocation leak
>
> drivers/media/platform/ti-vpe/cal.c | 13 ++++++++-----
> 1 file changed, 8 insertions(+), 5 deletions(-)

Reviewed-by: Tomi Valkeinen <[email protected]>

Tomi

--
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki