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Piccoli" Cc: Kees Cook , Alexander Viro , Tony Luck , linux-hardening@vger.kernel.org, Luis Henriques , linux-kernel@vger.kernel.org Subject: [PATCH] pstore: inode: Only d_invalidate() is needed Date: Thu, 22 Feb 2024 10:34:31 -0800 Message-Id: <20240222183424.work.482-kees@kernel.org> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1869; i=keescook@chromium.org; h=from:subject:message-id; bh=4bS0TVmSCUPqoUf6s/inM/xSKlKTIsOpdrrMKBI49sU=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBl15O2wYWUWyoP3QKNOPh3mrCkRKF9q2EA8CvnY FXsTrEplXuJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZdeTtgAKCRCJcvTf3G3A JjydD/9f4FX3OVEjwZ0fXfY04dKcuWu2AUZmsPhfgk/M3jcN8bvvcOM4l5INP/5Wsk8QBA3FCbU lDCJUdtEDwSTHiSLfhpYtOWhLAMZsuJFqyzCq8hLF9ci64XbJ/Uup6lDL0wPSN71ah3ZopZrn/J o2BMfLll63i2IK+gMZyOa10ACj1lO1tTPCLGLJAYraA68Cot2BwzpQXfxUnrPKajkDSv0moZfxi khoWppIeHQxg/4lqCLC044T6vi0VNKRMH4JfGAZhmghSR8C+NoNWALeJqQRADxiOCjrte/7CX44 1WuCyqJgEJEJs4YZw7WTKGRo4Exgfx2BIRDfYFyLVWbV8uJcuSN8dRVmkLdEEYrlsOp04U9l3AM uXeYYwg+OlPdQbRRmTx1FDTO817kbuCBbxcsHoaE86UqTAC9nA2Kgy3+Vmrc7EO+zjbaTTPXqo1 HByprXyr7HegXwiWgpPGovxotZJFM6tfK03zQCDvbEhA31F8FPwUW1RTqytHvtL4ceV4J3wiOLl d36nMAKKb8D9DOXXHkNhdejB/jFnCjDiKw+6W1gqJd1RDP3vjOztRvjfbHiiEL6Bi2u4IAPFTuK W4UOEgpm1ZktZwm+q1tL5N+ePpZyHrW2cXihQYcpzq5nx66t+x+a/UUh1Kzts2KgQ+bWICjC3oN ZxpWBfr +ho2AWsw== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1791625625564369652 X-GMAIL-MSGID: 1791625625564369652 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 Fixes: 609e28bb139e ("pstore: Remove filesystem records when backend is unregistered") Signed-off-by: Kees Cook --- Cc: "Guilherme G. Piccoli" Cc: Tony Luck Cc: linux-hardening@vger.kernel.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 d0d9bfdad30c..56815799ce79 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; } /*