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 --- 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 d0d9bfdad30cc..56815799ce798 100644 --- a/fs/pstore/inode.c +++ b/fs/pstore/inode.c @@ -307,7 +307,6 @@ 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) @@ -317,11 +316,8 @@ 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; } } @@ -329,7 +325,7 @@ int pstore_put_backend_records(struct pstore_info *psi)
inode_unlock(d_inode(root));
- return rc; + return 0; }
/*