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=1792774232; b=GvdSBG0WnS1uBjQqrfogie6QO4HL7jiZ7tW0kF/8EMDhpeuDzpNkGtRDOHJ44mvcsVkR uCoiAiEyDhYLXWXQc79tssDuXwN5bUc5/LXI2FSv0Y8pn6aqvBj3KtjcCaFy6WRQbcHUb p7OzjCvl9xKuGj5gJYa/kXW1wrAH/rTPKkXGL39bA674O7UYAOB4Pv4goTHwTXUC2Cc1S MA4vneKR09D4wUTnOGWFLaUZxOxoSB3TRnIhKtCrfHyavE1b06c66NUX3Hq06Br8JK7Cx 42mpbFstQu6Q8rIkbe6ED9PTIkv/pMbOhopaCtTp3z9ak6g0xe3oFUxH/Fd3kjC0roQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792774232; 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=mzukxdZPzMS2Ry5O+DByUuq8aPsyke/MPWOxuzQssYg=; b=ZdKpysGDXwUX7kQ7LG39frVzxTOpHZl3upbNNh0u/OEzljBw7DSXNaq5FWwOvxMQHfhb Da9RdEDvdjjLsplH5MjmIBKUT/9uBU0wECpXxkVuDR6s46PLg5jNa3GZoLN9gH4ue8sRE 6VJBC9DkJa+DGL4GH6/ImXcEj1vepJAzrQCK+zoBsQhahikldZKAUVc5xc305nprQ1kMC +j3mnbfASMaYaALPkHwBa8ZduAWboiR9/cFEIWt93LeCkoifWaCC5QrKH0lVDTMg0sION 1foG8b3moZvNSaCqZRA6Wb/EnukzjC6X95/UK2nXOztbhCF1MwTLwOOU/5BFIJYAfQw== 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=BVdvngAm; 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 4F57D606A31B; Fri, 23 Oct 2026 16:50:32 +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=BVdvngAm Received: by smtp.kernel.org (Postfix) with ESMTPSA id 666421F01825; Fri, 23 Oct 2026 16:50:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792774231; bh=mzukxdZPzMS2Ry5O+DByUuq8aPsyke/MPWOxuzQssYg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=BVdvngAmf5z2qjBvbKXURQGt6NCGAfgJlsqvAKIdPuoZa/j+iSC5Wwd/ydevcQeKV ZdM3RRymGo7CYSHa9H8uRkglb5eyuQ7lVJb+pjtmoxJ60PJMi/u0n4k4Q20AFsIbon 1nOnbanQglo+u/YnupXJ3tRKhpfZgDCu2r1f7KkU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Christian Brauner (Amutable)" , Sasha Levin Subject: [PATCH 6.18 164/193] ntfs3: free the sbi after a grace period Date: Fri, 23 Oct 2026 18:37:21 +0200 Message-ID: <20261023163718.094007711@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 [ Upstream commit c01b091b06412d3b1b53d8c2925f6de586c8a2fc ] If the "nocase" mount option ntfs3 uses custom hash and dentry compare functions. Both access ntfs3 superblock private information in rcu pathwalk. ntfs_put_super() and ntfs3_kill_sb() drop the info without any rcu delay. A lookup that's still inside the filesystem when the last reference to the mount is dropped causes a UAF. With a pathwalk held up in ntfs_d_hash() while the last reference to the mount goes away: BUG: KASAN: slab-use-after-free in ntfs_nls_to_utf16+0x752/0x940 Read of size 8 at addr ff1100010453c850 by task walker/99 Call Trace: ntfs_nls_to_utf16+0x752/0x940 ntfs_d_hash+0x22b/0x500 link_path_walk+0x11ad/0x1d30 path_lookupat+0x63/0xb00 filename_lookup+0x1f1/0x5b0 vfs_statx+0xd7/0x3b0 [...] Allocated by task 95: __kmalloc_cache_noprof+0x249/0x560 ntfs_init_fs_context+0x2db/0x5a0 alloc_fs_context+0x52e/0xc70 [...] Freed by task 98: kfree+0x1db/0x5b0 deactivate_locked_super+0x9c/0xf0 cleanup_mnt+0x9f/0x130 task_work_run+0x131/0x250 The bug is currently masked by the grace period in namespace_unlock() for umount(2). Keep the necessary information until the filesystem private info is freed and free it with an rcu delay. ntfs3_free_sbi() now runs from an rcu callback and drops the upcase table via ntfs_put_shared(). So switch s_shared_lock over to spin_lock_bh(). Otherwise the callback can deadlock against a task holding the lock on the same cpu. Fixes: a3a956c78efa ("fs/ntfs3: Add option "nocase"") Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20261009-work-fixes-rcu-v1-7-7446d2d335e6@kernel.org Signed-off-by: Christian Brauner (Amutable) Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- fs/ntfs3/ntfs_fs.h | 1 + fs/ntfs3/super.c | 33 +++++++++++++++++++++------------ 2 files changed, 22 insertions(+), 12 deletions(-) --- a/fs/ntfs3/ntfs_fs.h +++ b/fs/ntfs3/ntfs_fs.h @@ -209,6 +209,7 @@ struct ntfs_index { /* Ntfs file system in-core superblock data. */ struct ntfs_sb_info { struct super_block *sb; + struct rcu_head rcu; u32 discard_granularity; u64 discard_granularity_mask_inv; // ~(discard_granularity_mask_inv-1) --- a/fs/ntfs3/super.c +++ b/fs/ntfs3/super.c @@ -194,7 +194,7 @@ void *ntfs_set_shared(void *ptr, u32 byt void *ret = NULL; int i, j = -1; - spin_lock(&s_shared_lock); + spin_lock_bh(&s_shared_lock); for (i = 0; i < ARRAY_SIZE(s_shared); i++) { if (!s_shared[i].cnt) { j = i; @@ -212,7 +212,7 @@ void *ntfs_set_shared(void *ptr, u32 byt s_shared[j].cnt = 1; ret = ptr; } - spin_unlock(&s_shared_lock); + spin_unlock_bh(&s_shared_lock); return ret; } @@ -229,7 +229,7 @@ void *ntfs_put_shared(void *ptr) void *ret = ptr; int i; - spin_lock(&s_shared_lock); + spin_lock_bh(&s_shared_lock); for (i = 0; i < ARRAY_SIZE(s_shared); i++) { if (s_shared[i].cnt && s_shared[i].ptr == ptr) { if (--s_shared[i].cnt) @@ -237,7 +237,7 @@ void *ntfs_put_shared(void *ptr) break; } } - spin_unlock(&s_shared_lock); + spin_unlock_bh(&s_shared_lock); return ret; } @@ -684,6 +684,8 @@ static noinline void ntfs3_put_sbi(struc static void ntfs3_free_sbi(struct ntfs_sb_info *sbi) { + if (sbi->options) + put_mount_options(sbi->options); kfree(sbi->new_rec); kvfree(ntfs_put_shared(sbi->upcase)); kvfree(sbi->def_table); @@ -695,6 +697,11 @@ static void ntfs3_free_sbi(struct ntfs_s kfree(sbi); } +static void ntfs3_free_sbi_rcu(struct rcu_head *head) +{ + ntfs3_free_sbi(container_of(head, struct ntfs_sb_info, rcu)); +} + static void ntfs_put_super(struct super_block *sb) { struct ntfs_sb_info *sbi = sb->s_fs_info; @@ -704,11 +711,11 @@ static void ntfs_put_super(struct super_ /* Mark rw ntfs as clear, if possible. */ ntfs_set_state(sbi, NTFS_DIRTY_CLEAR); - if (sbi->options) { - put_mount_options(sbi->options); - sbi->options = NULL; - } - + /* + * The mount options stay until the sbi is freed: ->d_hash() and + * ->d_compare() of a pathwalk in rcu mode read the nls table through + * them. + */ ntfs3_put_sbi(sbi); } @@ -1865,9 +1872,11 @@ static void ntfs3_kill_sb(struct super_b kill_block_super(sb); - if (sbi->options) - put_mount_options(sbi->options); - ntfs3_free_sbi(sbi); + /* + * A pathwalk in rcu mode may still be in ->d_hash() or ->d_compare() + * and read the upcase table and the nls table through the sbi. + */ + call_rcu(&sbi->rcu, ntfs3_free_sbi_rcu); } // clang-format off