From: Alex Williamson <alex.williamson@nvidia.com> mainline inclusion from mainline-v7.2-rc2 commit dc7fe87de492ea7f33a72b78d26650b75bf37f4f category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/16762 CVE: CVE-2026-64473 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- VFIO device debugfs files created with debugfs_create_devm_seqfile() store a devres allocated debugfs_devm_entry as inode private data. vfio_unregister_group_dev() currently calls vfio_device_del() before vfio_device_debugfs_exit(), but device_del() releases devres. This can leave debugfs entries visible with stale inode private data while unregister waits for userspace references to drain. Remove the per-device debugfs tree before vfio_device_del(). The debugfs view is diagnostic only, so losing it at the start of unregister is preferable to preserving entries whose backing storage may already have been released. Complete the teardown by clearing the per-device debugfs root after removal. This matches the global debugfs root cleanup and prevents future users from mistaking a removed dentry for a live debugfs tree during the remainder of unregister. Fixes: 2202844e4468 ("vfio/migration: Add debugfs to live migration driver") Reported-by: Sashiko AI Review <sashiko-bot@kernel.org> Link: https://lore.kernel.org/r/20260615192725.6A2221F000E9@smtp.kernel.org Cc: stable@vger.kernel.org Cc: Longfang Liu <liulongfang@huawei.com> Assisted-by: OpenAI Codex:gpt-5 Signed-off-by: Alex Williamson <alex.williamson@nvidia.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Link: https://lore.kernel.org/r/20260615204717.735302-1-alex.williamson@nvidia.com Signed-off-by: Alex Williamson <alex@shazbot.org> Signed-off-by: Yuwei Zhang <zhangyuwei20@huawei.com> --- drivers/vfio/debugfs.c | 1 + drivers/vfio/vfio_main.c | 8 +++++++- 2 files changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/vfio/debugfs.c b/drivers/vfio/debugfs.c index 298bd866f157..53b678a16d4b 100644 --- a/drivers/vfio/debugfs.c +++ b/drivers/vfio/debugfs.c @@ -78,6 +78,7 @@ void vfio_device_debugfs_init(struct vfio_device *vdev) void vfio_device_debugfs_exit(struct vfio_device *vdev) { debugfs_remove_recursive(vdev->debug_root); + vdev->debug_root = NULL; } void vfio_debugfs_create_root(void) diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c index e9c71005bff5..03d034ece8c9 100644 --- a/drivers/vfio/vfio_main.c +++ b/drivers/vfio/vfio_main.c @@ -350,6 +350,13 @@ void vfio_unregister_group_dev(struct vfio_device *device) */ vfio_device_group_unregister(device); + /* + * Remove debugfs before device_del(), which releases devres. Some + * debugfs entries are created with debugfs_create_devm_seqfile() and + * therefore rely on devres-managed inode private data. + */ + vfio_device_debugfs_exit(device); + /* * Balances vfio_device_add() in register path, also prevents * new device opened by userspace in the cdev path. @@ -379,7 +386,6 @@ void vfio_unregister_group_dev(struct vfio_device *device) } } - vfio_device_debugfs_exit(device); /* Balances vfio_device_set_group in register path */ vfio_device_remove_group(device); } -- 2.22.0