[PATCH v9 5/5] drm/panthor: Fix race condition when gathering fdinfo group samples

Adrián Larumbe
2025-01-23T22:54:39Z

Commit e16635d88fa0 ("drm/panthor: add DRM fdinfo support") failed to
protect access to groups with an xarray lock, which could lead to
use-after-free errors.

Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
Fixes: e16635d88fa0 ("drm/panthor: add DRM fdinfo support")
---
drivers/gpu/drm/panthor/panthor_sched.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c
index e6c08a694e41..1d283b4bab86 100644
--- a/drivers/gpu/drm/panthor/panthor_sched.c
+++ b/drivers/gpu/drm/panthor/panthor_sched.c
@@ -2865,6 +2865,7 @@ void panthor_fdinfo_gather_group_samples(struct panthor_file *pfile)
if (IS_ERR_OR_NULL(gpool))
return;

+ xa_lock(&gpool->xa);
xa_for_each(&gpool->xa, i, group) {
mutex_lock(&group->fdinfo.lock);
pfile->stats.cycles += group->fdinfo.data.cycles;
@@ -2873,6 +2874,7 @@ void panthor_fdinfo_gather_group_samples(struct panthor_file *pfile)
group->fdinfo.data.time = 0;
mutex_unlock(&group->fdinfo.lock);
}
+ xa_unlock(&gpool->xa);
}

static void group_sync_upd_work(struct work_struct *work)
--
2.47.1