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=1792594173; b=08hRs1hWeEJVnTD17zYzRsAlGqiD0MB1p++yJMlxD9t+1puVra1BhBOsibqPVw82lRsM m3lwbA1E5rjMfcz8GOXiZrccdnkdiS6D9RoxDmUXCdaBpVj4687A2gJNqoEHQ5hWB7vKT 1hF6NIWWDcPYBNhgF/ZYf6VQU7gB7Q1zRAR/vPjVjXy+n2yRmO98iRmbCwSpbb5VPlPnQ ZRcEBh2GEiEUqDXfhI4Ad3W266rj8NqVbWkHzPFotddwHhHfgt9kfsxaAXTCB4mEqeu2M VlsooZQ8Xw7dFdee8FTIhM2Yng9/wcf317kkC/JMksWcfdpUD2JDP1hhTZsNZz2rcBQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792594173; h=Received:DKIM-Signature:Subject:To:Cc:From:Date:Message-ID: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=RWyg0xZKd7GHBTIVZmwg6QhIh+/Xi/oAsBZPBpe4QN4=; b=q2vKLHobS+4ORRpJJVJ3HJatYcAZy5RluquFMzi/u74P3HEdoACuI0YRh6OEdNWKzo+q UUZ/6Iz1qNW6y96QyzLnxwGqvARVKq5wJ3Q4iPFLNjrdFUs3uxJc4DQucA5aSfyuAXMe6 XKBUfO8c7uuh141WFo5J+ujNvSqYpR7cmmBtncrof2FzvMG6jXppYwqBhTTNkeUFiBRyz HJhB9q5kYSfi/pk903HAHGOJbPOtV8/a/YK+HQ92yew8iTIAYnwEpSJ8xOPoReNGmACkB FTTYAHf90m4D3veL8UkNvaWpmcujBBRSNKm2yrrsYSgketZisYdynd0YKr81c09Lq1w== 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=2tS69v0Z; 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 4E4B8606A31D for ; Wed, 21 Oct 2026 14:49:33 +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=2tS69v0Z Received: by smtp.kernel.org (Postfix) with ESMTPSA id 56F831F000C1; Wed, 21 Oct 2026 14:49:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792594172; bh=RWyg0xZKd7GHBTIVZmwg6QhIh+/Xi/oAsBZPBpe4QN4=; h=Subject:To:Cc:From:Date; b=2tS69v0ZZDUDHqVasRG7vHgaDJagIExHvUqp6lzEc3sltwXo/lC9tRIQ7yXWXCOhr 8d3pIWdpoT8M1IJguIabG0NMYw7Kt5MFiH3vHqStg8pTSKr4CFd5Hj5TTylLima7SD IVciz1KcpVcFJCGWhHKk3/kZ1C+hEiDyoQ1Lzzq0= Subject: FAILED: patch "[PATCH] ntfs3: free the sbi after a grace period" failed to apply to 6.18-stable tree To: brauner@kernel.org Cc: From: Date: Wed, 21 Oct 2026 16:38:57 +0200 Message-ID: <2026102157-deuce-giblet-3fc8@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y git checkout FETCH_HEAD git cherry-pick -x c01b091b06412d3b1b53d8c2925f6de586c8a2fc # git commit -s git send-email --to '' --in-reply-to '2026102157-deuce-giblet-3fc8@gregkh' --subject-prefix 'PATCH 6.18.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From c01b091b06412d3b1b53d8c2925f6de586c8a2fc Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Fri, 9 Oct 2026 23:51:57 +0200 Subject: [PATCH] ntfs3: free the sbi after a grace period 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) diff --git a/fs/ntfs3/ntfs_fs.h b/fs/ntfs3/ntfs_fs.h index 5811d89d67b3..bbcd2e02bf63 100644 --- a/fs/ntfs3/ntfs_fs.h +++ b/fs/ntfs3/ntfs_fs.h @@ -211,6 +211,7 @@ 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) diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c index f4a42a0c73a4..841f9068d82f 100644 --- a/fs/ntfs3/super.c +++ b/fs/ntfs3/super.c @@ -196,7 +196,7 @@ void *ntfs_set_shared(void *ptr, u32 bytes) 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; @@ -214,7 +214,7 @@ void *ntfs_set_shared(void *ptr, u32 bytes) s_shared[j].cnt = 1; ret = ptr; } - spin_unlock(&s_shared_lock); + spin_unlock_bh(&s_shared_lock); return ret; } @@ -231,7 +231,7 @@ 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) @@ -239,7 +239,7 @@ void *ntfs_put_shared(void *ptr) break; } } - spin_unlock(&s_shared_lock); + spin_unlock_bh(&s_shared_lock); return ret; } @@ -708,6 +708,8 @@ static noinline void ntfs3_put_sbi(struct ntfs_sb_info *sbi) 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); @@ -719,6 +721,11 @@ static void ntfs3_free_sbi(struct ntfs_sb_info *sbi) 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; @@ -728,11 +735,11 @@ static void ntfs_put_super(struct super_block *sb) /* 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); } @@ -1939,9 +1946,11 @@ static void ntfs3_kill_sb(struct super_block *sb) 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