[PATCH v2] media: meson: vdec: Fix memory leak in error path of vdec_open

[Anand Moon]

Hi Nicolas.

Thanks for your review comments
On Fri, 8 May 2026 at 23:28, Nicolas Dufresne <nicolas at ndufresne.ca> wrote:
>
> Hi,
>
> sorry I missed your patch, catching up now.
>
>
> Le samedi 21 mars 2026 à 12:24 +0530, Anand Moon a écrit :
> > The vdec_open and vdec_close functions in the Meson VDEC driver failed
> > to release several resources, leading to memory leaks and potential
> > use-after-free scenarios.
> >
> > This patch addresses:
> > - Missing v4l2_ctrl_handler_free() in both the close path and error
> >   exit of the open path, preventing control memory leaks.
> > - A leak of the M2M context if vdec_init_ctrls() failed.
> >
> > The error labels in vdec_open() have been reordered to ensure a proper
> > Last-In-First-Out (LIFO) teardown of all initialized resources.
> >
> > This was identified via kmemleak:
> > unreferenced object 0xffff0000205d6878 (size 8):
> >   comm "v4l_id", pid 5289, jiffies 4294938580
> >   hex dump (first 8 bytes):
> >     40 d2 49 18 00 00 ff ff                          @.I.....
> >   backtrace (crc d3204599):
> >     kmemleak_alloc+0xc8/0xf0
> >     __kvmalloc_node_noprof+0x60c/0x850
> >     v4l2_ctrl_handler_init_class+0x1b4/0x2e8 [videodev]
> >     vdec_open+0x1f4/0x788 [meson_vdec]
> >     v4l2_open+0x144/0x460 [videodev]
> >     chrdev_open+0x1ac/0x500
> >     do_dentry_open+0x3f0/0xfe8
> >     vfs_open+0x68/0x320
> >     do_open+0x2d8/0x9a8
> >     path_openat+0x1d0/0x4f0
> >     do_filp_open+0x190/0x380
> >     do_sys_openat2+0xf8/0x1b0
> >     __arm64_sys_openat+0x13c/0x1e8
> >     invoke_syscall+0xdc/0x268
> >     el0_svc_common.constprop.0+0x178/0x258
> >     do_el0_svc+0x4c/0x70
> >
> > Cc: Nicolas Dufresne <nicolas at ndufresne.ca>
> > Fixes: 3e7f51bd9607 ("media: meson: add v4l2 m2m video decoder driver")
> > Signed-off-by: Anand Moon <linux.amoon at gmail.com>
> > ---
> > v1: https://lore.kernel.org/all/20260304100557.126488-1-linux.amoon@gmail.com/
> >    tried to address the issue reported by Nicolas
> >    improve the commit message.
> > ---
> >  drivers/staging/media/meson/vdec/vdec.c | 9 ++++++---
> >  1 file changed, 6 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/staging/media/meson/vdec/vdec.c
> > b/drivers/staging/media/meson/vdec/vdec.c
> > index 4b77ec1af5a76..3a5e4ebe0b34c 100644
> > --- a/drivers/staging/media/meson/vdec/vdec.c
> > +++ b/drivers/staging/media/meson/vdec/vdec.c
> > @@ -877,7 +877,7 @@ static int vdec_open(struct file *file)
> >       if (IS_ERR(sess->m2m_dev)) {
> >               dev_err(dev, "Fail to v4l2_m2m_init\n");
> >               ret = PTR_ERR(sess->m2m_dev);
> > -             goto err_free_sess;
> > +             goto err_m2m_release;
>
> If m2m_dev creation failed, why do you want to call v4l2_m2m_release() ?
>
I don’t recall the exact details, but the current handling appears incorrect.
I’ve prepared the following fix to resolve the issue, based on
sashiko’s suggestion.

[1] https://sashiko.dev/#/patchset/20260321065408.209723-1-linux.amoon%40gmail.com

-----8<----------8<--------
$ git diff drivers/staging/media/meson/vdec/vdec.c
diff --git a/drivers/staging/media/meson/vdec/vdec.c
b/drivers/staging/media/meson/vdec/vdec.c
index 4b77ec1af5a7..a039d925c0fe 100644
--- a/drivers/staging/media/meson/vdec/vdec.c
+++ b/drivers/staging/media/meson/vdec/vdec.c
@@ -889,7 +889,7 @@ static int vdec_open(struct file *file)

        ret = vdec_init_ctrls(sess);
        if (ret)
-               goto err_m2m_release;
+               goto err_m2m_ctx_release;

        sess->pixfmt_cap = formats[0].pixfmts_cap[0];
        sess->fmt_out = &formats[0];
@@ -913,6 +913,8 @@ static int vdec_open(struct file *file)

        return 0;

+err_m2m_ctx_release:
+       v4l2_m2m_ctx_release(sess->m2m_ctx);
 err_m2m_release:
        v4l2_m2m_release(sess->m2m_dev);
 err_free_sess:
-----8<----------8<--------

Thanks
-Anand