Re: [PATCH] coresight: fix resource leaks on path build failure

[Suzuki K Poulose]

On 09/11/2026 10:34, James Clark wrote:
> On 09/11/2026 01:24, Jie Gan wrote:
> > On 5/13/2026 9:32 AM, Jie Gan wrote:
> > > Two related leaks when _coresight_build_path() encounters an error after
> > > coresight_grab_device() has already incremented the pm_runtime, module,
> > > and device references for a node:
> > >
> > > 1. In _coresight_build_path(), if kzalloc_obj() for the path node fails
> > >     after coresight_grab_device() succeeds, coresight_drop_device() was
> > >     never called, permanently leaking all three references.
> > >
> > > 2. In coresight_build_path(), on failure the partial path was freed with
> > >     kfree(path) instead of coresight_release_path(path).  kfree() only
> > >     frees the coresight_path struct itself; it does not iterate 
> > > path_list
> > >     to call coresight_drop_device() and kfree() for each coresight_node
> > >     already added by deeper recursive calls, leaking both the 
> > > pm_runtime,
> > >     module, and device references and the node memory for every element
> > >     on the partial path.
> > >
> > > Fix both by adding coresight_drop_device() in the OOM unwind of
> > > _coresight_build_path(), and replacing kfree(path) with
> > > coresight_release_path(path) in coresight_build_path().
> > >
> > > Fixes: 32b0707a4182 ("coresight: Add try_get_module() in 
> > > coresight_grab_device()")
> > > Fixes: b3e94405941e ("coresight: associating path with session rather 
> > > than tracer")
> > > Signed-off-by: Jie Gan <jie.gan@xxxxxxxxxxxxxxxx>
> >
> > Gentle ping.
> >
> > > ---
> > >   drivers/hwtracing/coresight/coresight-core.c | 6 ++++--
> > >   1 file changed, 4 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/ 
> > > hwtracing/coresight/coresight-core.c
> > > index 46f247f73cf6..c1354ea8e11d 100644
> > > --- a/drivers/hwtracing/coresight/coresight-core.c
> > > +++ b/drivers/hwtracing/coresight/coresight-core.c
> > > @@ -825,8 +825,10 @@ static int _coresight_build_path(struct 
> > > coresight_device *csdev,
> > >           return ret;
> > >       node = kzalloc_obj(struct coresight_node);
> > > -    if (!node)
> > > +    if (!node) {
> > > +        coresight_drop_device(csdev);
> > >           return -ENOMEM;
> > > +    }
> > >       node->csdev = csdev;
> > >       list_add(&node->link, &path->path_list);
> > > @@ -851,7 +853,7 @@ struct coresight_path 
> > > *coresight_build_path(struct coresight_device *source,
> > >       rc = _coresight_build_path(source, source, sink, path);
> > >       if (rc) {
> > > -        kfree(path);
> > > +        coresight_release_path(path);
>
> @Suzuki, there's a conflict here. This will need to be 
> coresight_release_path_locked() if we also take "coresight: etm-perf: 
> Serialize AUX topology access" from my Sashiko fixes.

The changes needed by the patch are already what your patches does.
Apologies Jie Gan, I have merged Jamess series which solves everything.
So, we can ignore this one.

Cheers
Suzuki