When bailing out due to group_priority_permit() failure, the queue_args need to be freed. Fix it by rearranging the function to use the goto-on-error pattern, such that the success case flows straight without indentation while error cases jump forward to cleanup.
Cc: stable@vger.kernel.org Fixes: 5f7762042f8a ("drm/panthor: Restrict high priorities on group_create") Signed-off-by: Jann Horn jannh@google.com --- testcase: ``` #include <err.h> #include <fcntl.h> #include <stddef.h> #include <sys/ioctl.h> #include <drm/panthor_drm.h>
#define SYSCHK(x) ({ \ typeof(x) __res = (x); \ if (__res == (typeof(x))-1) \ err(1, "SYSCHK(" #x ")"); \ __res; \ })
#define GPU_PATH "/dev/dri/by-path/platform-fb000000.gpu-card"
int main(void) { int fd = SYSCHK(open(GPU_PATH, O_RDWR));
while (1) { struct drm_panthor_queue_create qc[16] = {}; struct drm_panthor_group_create gc = { .queues = { .stride = sizeof(struct drm_panthor_queue_create), .count = 16, .array = (unsigned long)qc }, .priority = PANTHOR_GROUP_PRIORITY_HIGH+1/*invalid*/ }; ioctl(fd, DRM_IOCTL_PANTHOR_GROUP_CREATE, &gc); } } ```
I have tested that without this patch, after running the testcase for a few seconds and then manually killing it, 2G of RAM in kmalloc-128 have been leaked. With the patch applied, the memory leak is gone.
(By the way, get_maintainer.pl suggests that I also send this patch to the general DRM maintainers and the DRM-misc maintainers; looking at MAINTAINERS, it looks like it is normal that the general DRM maintainers are listed for everything under drivers/gpu/, but DRM-misc has exclusion rules for a bunch of drivers but not panthor. I don't know if that is intentional.) --- drivers/gpu/drm/panthor/panthor_drv.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c index c520f156e2d73f7e735f8bf2d6d8e8efacec9362..815c23cff25f305d884e8e3e263fa22888f7d5ce 100644 --- a/drivers/gpu/drm/panthor/panthor_drv.c +++ b/drivers/gpu/drm/panthor/panthor_drv.c @@ -1032,14 +1032,15 @@ static int panthor_ioctl_group_create(struct drm_device *ddev, void *data,
ret = group_priority_permit(file, args->priority); if (ret) - return ret; + goto out;
ret = panthor_group_create(pfile, args, queue_args); - if (ret >= 0) { - args->group_handle = ret; - ret = 0; - } + if (ret < 0) + goto out; + args->group_handle = ret; + ret = 0;
+out: kvfree(queue_args); return ret; }
--- base-commit: 9f8e716d46c68112484a23d1742d9ec725e082fc change-id: 20241113-panthor-fix-gcq-bailout-2d9ac36590ed