From: Theodore Ts'o Date: Sat, 21 Aug 2021 03:44:17 +0000 (-0400) Subject: ext4: fix race writing to an inline_data file while its xattrs are changing X-Git-Tag: v4.4.284~134 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=69d82df68fbc5e368820123200d7b88f6c058350;p=thirdparty%2Fkernel%2Fstable.git 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: f19d5870cbf72 ("ext4: add normal write support for inline data") Reported-by: syzbot+13146364637c7363a7de@syzkaller.appspotmail.com Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c index df585267d3c25..6f5e292e86f72 100644 --- a/fs/ext4/inline.c +++ b/fs/ext4/inline.c @@ -746,6 +746,12 @@ 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);