linux-kernel - [PATCH 5.13 01/24] ext4: fix race writing to an inline

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210906125449.162386842@linuxfoundation.org>
Date:   Mon,  6 Sep 2021 14:55:30 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, stable@...nel.org,
        syzbot+13146364637c7363a7de@...kaller.appspotmail.com,
        Theodore Tso <tytso@....edu>
Subject: [PATCH 5.13 01/24] ext4: fix race writing to an inline_data file while its xattrs are changing

From: Theodore Ts'o <tytso@....edu>

commit a54c4613dac1500b40e4ab55199f7c51f028e848 upstream.

The location of the system.data extended attribute can change whenever
xattr_sem is not taken.  So we need to recalculate the i_inline_off
field since it mgiht have changed between ext4_write_begin() and
ext4_write_end().

This means that caching i_inline_off is probably not helpful, so in
the long run we should probably get rid of it and shrink the in-memory
ext4 inode slightly, but let's fix the race the simple way for now.

Cc: stable@...nel.org
Fixes: f19d5870cbf72 ("ext4: add normal write support for inline data")
Reported-by: syzbot+13146364637c7363a7de@...kaller.appspotmail.com
Signed-off-by: Theodore Ts'o <tytso@....edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/ext4/inline.c |    6 ++++++
 1 file changed, 6 insertions(+)

--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -750,6 +750,12 @@ int ext4_write_inline_data_end(struct in
 	ext4_write_lock_xattr(inode, &no_expand);
 	BUG_ON(!ext4_has_inline_data(inode));
 
+	/*
+	 * ei->i_inline_off may have changed since ext4_write_begin()
+	 * called ext4_try_to_write_inline_data()
+	 */
+	(void) ext4_find_inline_data_nolock(inode);
+
 	kaddr = kmap_atomic(page);
 	ext4_write_inline_data(inode, &iloc, kaddr, pos, len);
 	kunmap_atomic(kaddr);