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=1792773983; b=1I6kP5+cDr7AlUoZ3sJhCZTtUPGGUOHEkT3Lx4Yoj+nJO2iZv98XzrL7Dp2tR8osZm4e saSrOdyDevKYSpc07HlrBBzx1TvqFU8q4aJ/zxUM/J8GxjCUrn0o+cKgG8F0Lfz6BLZ1Y fK36xCjgOuTIZHck61/dZEhaIpJA97ViGNY6U1i9d+iDZcP9rFqGbcfGhhHSeMKHgliBA 0znNoPjWfQSbnFJNTYQ1XgUZUyZtOYFuw/XxULkRZivJg6ZTNeR4Yfr9O9pn1CI8B4XAW 7JurB460eiI1yg38hE2LZaT7IzjznHqcTZjANwG2iSsd/sTe5nbage/F+ljYNn75chw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792773983; 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=1OIAxuYjQjU3t+U1v4KrY/gMiNMRBiO6ZvQct43bNh4=; b=M78d+EtkEBCLRiVoWqTdN2i3ZfxKbjzk6FWRB+mKI0SseQY+oreQXuvBWblx8iAzBG06 lXznjP5QhCyhMtu3liLzLaPP4wmiK4yhpkYRU4uI5y3gDISk1ULiqAiaaXJf2Zr1GW9MS 3xsjF+db9xy+81SBXXoVimi+9uQ+VgHin75LmimllvnjzSuk4SywLPYjuU1LgIDY+z9VW QwDg4Umm0bM3AxuLfjV3T/OE8rCDIAAXy2lZiFgIzj3NxHb661BdhtuU06kwfNhT6Yr87 kQ5zNSFOWLCHK8AF+lP9/bn+aHMUVsPa0wu7ky8Q7WhAesDhvJ69C29P6FyvV2fTzTA== 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=DdGIoysm; 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 B824F606A31B; Fri, 23 Oct 2026 16:46:22 +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=DdGIoysm Received: by smtp.kernel.org (Postfix) with ESMTPSA id 139E61F01825; Fri, 23 Oct 2026 16:46:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792773982; bh=1OIAxuYjQjU3t+U1v4KrY/gMiNMRBiO6ZvQct43bNh4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DdGIoysmAzYyefo+sJ9Jq5Un+7Qka3smeWbCB0gA1bvskj5gn0zHJss1UnYa2EzcA 44wE4Iz7LvyqYmz1r1gK4zTTtl1E27Xr2wDFRxHmzVxhY7jFhWQsqRIV6Szzf2GjPR /n9AB94iJMq/YVA/TGitxp1BHKIaSwFtVeEES0yc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Christian Brauner (Amutable)" , Steven Rostedt Subject: [PATCH 6.18 081/193] eventfs: Free the eventfs_inode after an rcu grace period too Date: Fri, 23 Oct 2026 18:35:58 +0200 Message-ID: <20261023163716.124706935@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261023163714.201276352@linuxfoundation.org> References: <20261023163714.201276352@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 6.18-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 @@ -91,6 +91,14 @@ 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. * @@ -112,7 +120,7 @@ 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)