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Message-Id: <20210906125448.209079113@linuxfoundation.org>
Date: Mon, 6 Sep 2021 14:55:47 +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 5.14 01/14] 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);
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