From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793210016; b=L9L00VoW5c/ZOkWgAnM6FdAksi4/gXDiXDxLGd1ofIIjqo/HOiNO4AunXtiJ+v0LBsiP IpcdYRO6958FJJcPaJTw5aJvA6nJW+d1H5d5i02rZCZSSCqLzGTmJgQI4oyGvdnncX5Bd skVX0Tai18bN7Od5eMX45FfWT/c00SeEEvtsJtxepDtaNgLjiamTp55a5GzHKEg4QVc6e hHFuXCPdfsapiKfvjTl2wWWI3BHCC6DVYDa40WQyGNEXZ+WEDXG1R1K62IZipM49Wy93Z LefYgymFiTTq4aP9Xhc+zsGA54gCpjak/xZrQ1wz7dgezX4nVKnxbijsLtbpP7XnJ9g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793210016; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=JG4XMFPJaFzWyqiiMw3H0XhIHBnCDJIgzNy8RJglFGY=; b=hWwGAWSCq08BBLohV8+vi846J2z8BmW0MhDy8xgzGyjcnrzbkdgwkBVz0gU7wLw50Gyf KBRt+boeIXmyAgU8beYz8+rmURjFGj3FSDR2eJ5DH9ov8e8Xqb+aTE+Fp/8rD6Q3+2yG5 lg2A4VNMxF+Cu+cnjRnC2Roeb5YiHnAPeLpSoxH23QyJjfTvaIyCfIJ7vphD1NpYrttI3 g11YNK3fVEsjkipq/OnOWcfPm3Z1BUMFPKwLcv1KPwFM4UXwiGzI2lY9J2OC+9fqiOAKE oB7HgZaKWfVExtyyg0LyPnSDTZxFtP98v1RZ8Jul99aaXLx9YLetnMOqOK2hul0EL4A== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=Vpoyseb+; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8F40C606A325; Wed, 28 Oct 2026 17:53:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=Vpoyseb+ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1B7EB1F031E2; Wed, 28 Oct 2026 17:53:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793210016; bh=JG4XMFPJaFzWyqiiMw3H0XhIHBnCDJIgzNy8RJglFGY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Vpoyseb+I/IVli887FZC6KunogX5WTSRu70xKB160LTSQCUqu9ol36IKstDIMzU2G 38R05QNWvLrXfaOOqofI07qbpA1rX8+Wz1ILxVv6VJ2TpHsFVnwi9zJR4bTDL1HCwe 3ydL2KsI3sNGb0e7FpnuUZx93payf+D2kBbKkLsM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Christian Brauner (Amutable)" , Steven Rostedt Subject: [PATCH 6.6 045/168] eventfs: Free the eventfs_inode after an rcu grace period too Date: Wed, 28 Oct 2026 17:59:41 +0100 Message-ID: <20261028165944.155815060@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028165943.089486480@linuxfoundation.org> References: <20261028165943.089486480@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christian Brauner commit 2cd88c498ecff8e22bf4c397b8eb226db70ac343 upstream. tracefs_d_revalidate() reads ->is_freed of the eventfs_inode that dentry->d_fsdata points to, and ->d_revalidate() is called in rcu pathwalk mode with nothing but rcu_read_lock() held. The dentry itself stays around for such a walker, but tracefs_d_release() drops its reference to the eventfs_inode when the dentry is killed, and release_ei() then frees it after a grace period of eventfs_srcu. An SRCU grace period doesn't wait for rcu_read_lock() sections, so the walker can read an eventfs_inode that is already gone. With a pathwalk held up in tracefs_d_revalidate() while the dentry goes away: BUG: KASAN: slab-use-after-free in tracefs_d_revalidate+0x76/0x90 Read of size 1 at addr ff1100010152d8d0 by task walker/97 Call Trace: tracefs_d_revalidate+0x76/0x90 lookup_fast+0x320/0x640 path_lookupat+0x160/0xb00 filename_lookup+0x1f1/0x5b0 vfs_statx+0xd7/0x3b0 vfs_fstatat+0x4d/0x90 __do_sys_newfstatat+0xa0/0x100 do_syscall_64+0x10e/0x5e0 entry_SYSCALL_64_after_hwframe+0x77/0x7f [...] Allocated by task 1: __kmalloc_cache_noprof+0x249/0x560 eventfs_create_dir+0x7a/0x590 event_create_dir+0x2fb/0xcf0 trace_add_event_call+0xbf/0x150 [...] Freed by task 11: kfree+0x1db/0x5b0 srcu_invoke_callbacks+0x3a3/0x620 process_one_work+0x937/0x1810 worker_thread+0x4f1/0xd60 Before commit 8e556432477e ("eventfs: Use SRCU for freeing eventfs_inodes") release_ei() used call_rcu(), which covered the walker, while eventfs_iterate() needs the SRCU grace period. Wait for both and chain call_rcu() from the SRCU callback. Cc: stable@vger.kernel.org Fixes: 8e556432477e ("eventfs: Use SRCU for freeing eventfs_inodes") Link: https://patch.msgid.link/20261009-work-fixes-rcu-v1-4-7446d2d335e6@kernel.org Signed-off-by: Christian Brauner (Amutable) Signed-off-by: Steven Rostedt Signed-off-by: Greg Kroah-Hartman --- fs/tracefs/event_inode.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -92,6 +92,14 @@ static void free_ei_rcu(struct rcu_head } } +/* read under eventfs_srcu and, by tracefs_d_revalidate(), in rcu pathwalk */ +static void free_ei_srcu(struct rcu_head *rcu) +{ + struct eventfs_inode *ei = container_of(rcu, struct eventfs_inode, rcu); + + call_rcu(&ei->rcu, free_ei_rcu); +} + /* * eventfs_inode reference count management. * @@ -113,7 +121,7 @@ static void release_ei(struct kref *ref) entry->release(entry->name, ei->data); } - call_srcu(&eventfs_srcu, &ei->rcu, free_ei_rcu); + call_srcu(&eventfs_srcu, &ei->rcu, free_ei_srcu); } static inline void put_ei(struct eventfs_inode *ei)