pstore: inode: Only d_invalidate() is needed
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:
parent
41bccc98fb
commit
a43e0fc5e9
@ -307,7 +307,6 @@ int pstore_put_backend_records(struct pstore_info *psi)
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{
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{
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struct pstore_private *pos, *tmp;
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struct pstore_private *pos, *tmp;
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struct dentry *root;
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struct dentry *root;
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int rc = 0;
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root = psinfo_lock_root();
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root = psinfo_lock_root();
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if (!root)
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if (!root)
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@ -317,11 +316,8 @@ int pstore_put_backend_records(struct pstore_info *psi)
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list_for_each_entry_safe(pos, tmp, &records_list, list) {
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list_for_each_entry_safe(pos, tmp, &records_list, list) {
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if (pos->record->psi == psi) {
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if (pos->record->psi == psi) {
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list_del_init(&pos->list);
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list_del_init(&pos->list);
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rc = simple_unlink(d_inode(root), pos->dentry);
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d_invalidate(pos->dentry);
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if (WARN_ON(rc))
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simple_unlink(d_inode(root), pos->dentry);
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break;
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d_drop(pos->dentry);
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dput(pos->dentry);
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pos->dentry = NULL;
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pos->dentry = NULL;
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}
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}
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}
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}
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@ -329,7 +325,7 @@ int pstore_put_backend_records(struct pstore_info *psi)
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inode_unlock(d_inode(root));
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inode_unlock(d_inode(root));
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return rc;
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return 0;
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}
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}
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/*
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/*
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