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Commit 9b3849ba authored by Theodore Ts'o's avatar Theodore Ts'o Committed by Greg Kroah-Hartman
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ext4: fix race writing to an inline_data file while its xattrs are changing 



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@kernel.org
Fixes: f19d5870 ("ext4: add normal write support for inline data")
Reported-by: default avatar <syzbot+13146364637c7363a7de@syzkaller.appspotmail.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c6bf0ed9

fs/ext4/inline.c

+6 −0
Original line number Diff line number Diff line
@@ -750,6 +750,12 @@ int ext4_write_inline_data_end(struct inode *inode, loff_t pos, unsigned len, 
	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);