This is a note to let you know that I've just added the patch titled ext4: fix race writing to an inline_data file while its xattrs are changing to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ext4-fix-race-writing-to-an-inline_data-file-while-its-xattrs-are-changing.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From a54c4613dac1500b40e4ab55199f7c51f028e848 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o <tytso@xxxxxxx> Date: Fri, 20 Aug 2021 23:44:17 -0400 Subject: ext4: fix race writing to an inline_data file while its xattrs are changing From: Theodore Ts'o <tytso@xxxxxxx> 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@xxxxxxxxxx Fixes: f19d5870cbf72 ("ext4: add normal write support for inline data") Reported-by: syzbot+13146364637c7363a7de@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/ext4/inline.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/fs/ext4/inline.c +++ b/fs/ext4/inline.c @@ -746,6 +746,12 @@ 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); Patches currently in stable-queue which might be from tytso@xxxxxxx are queue-4.4/ext4-fix-race-writing-to-an-inline_data-file-while-its-xattrs-are-changing.patch