From: Kees Cook <keescook@chromium.org>
[ Upstream commit a43e0fc5e9134a46515de2f2f8d4100b74e50de3 ]
Unloading a modular pstore backend with records in pstorefs would
trigger the dput() double-drop warning:
WARNING: CPU: 0 PID: 2569 at fs/dcache.c:762 dput.part.0+0x3f3/0x410
Using the combo of d_drop()/dput() (as mentioned in
Documentation/filesystems/vfs.rst) isn't the right approach here, and
leads to the reference counting problem seen above. Use d_invalidate()
and update the code to not bother checking for error codes that can
never happen.
Suggested-by: Alexander Viro <viro@zeniv.linux.org.uk>
Fixes: 609e28bb139e ("pstore: Remove filesystem records when backend is unregistered")
Signed-off-by: Kees Cook <keescook@chromium.org>
---
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-hardening@vger.kernel.org
[ Minor context change fixed. ]
Signed-off-by: Robert Garcia <rob_garcia@163.com>
---
fs/pstore/inode.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
index 14658b009f1b..f56e0b105be7 100644
--- a/fs/pstore/inode.c
+++ b/fs/pstore/inode.c
@@ -312,7 +312,6 @@ int pstore_put_backend_records(struct pstore_info *psi)
{
struct pstore_private *pos, *tmp;
struct dentry *root;
- int rc = 0;
root = psinfo_lock_root();
if (!root)
@@ -322,11 +321,8 @@ int pstore_put_backend_records(struct pstore_info *psi)
list_for_each_entry_safe(pos, tmp, &records_list, list) {
if (pos->record->psi == psi) {
list_del_init(&pos->list);
- rc = simple_unlink(d_inode(root), pos->dentry);
- if (WARN_ON(rc))
- break;
- d_drop(pos->dentry);
- dput(pos->dentry);
+ d_invalidate(pos->dentry);
+ simple_unlink(d_inode(root), pos->dentry);
pos->dentry = NULL;
}
}
@@ -334,7 +330,7 @@ int pstore_put_backend_records(struct pstore_info *psi)
inode_unlock(d_inode(root));
- return rc;
+ return 0;
}
/*
--
2.34.1