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pstore: inode: Only d_invalidate() is needed

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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: 609e28bb13 ("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
This commit is contained in:
Kees Cook 2024-02-22 09:48:46 -08:00
parent 41bccc98fb
commit a43e0fc5e9
1 changed files with 3 additions and 7 deletions
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10
fs/pstore/inode.c
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@ -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;
}
/*