]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
nilfs2: fix possible out-of-bounds segment allocation in resize ioctl
authorRyusuke Konishi <konishi.ryusuke@gmail.com>
Wed, 24 May 2023 09:43:48 +0000 (18:43 +0900)
committerAndrew Morton <akpm@linux-foundation.org>
Mon, 12 Jun 2023 18:31:51 +0000 (11:31 -0700)
commitfee5eaecca86afa544355569b831c1f90f334b85
tree51a767318167dcf36ddad6c64e46068d98306d17
parent88ac3bbcf73853880a9b2a65c67e6854390741cc
nilfs2: fix possible out-of-bounds segment allocation in resize ioctl

Syzbot reports that in its stress test for resize ioctl, the log writing
function nilfs_segctor_do_construct hits a WARN_ON in
nilfs_segctor_truncate_segments().

It turned out that there is a problem with the current implementation of
the resize ioctl, which changes the writable range on the device (the
range of allocatable segments) at the end of the resize process.

This order is necessary for file system expansion to avoid corrupting the
superblock at trailing edge.  However, in the case of a file system
shrink, if log writes occur after truncating out-of-bounds trailing
segments and before the resize is complete, segments may be allocated from
the truncated space.

The userspace resize tool was fine as it limits the range of allocatable
segments before performing the resize, but it can run into this issue if
the resize ioctl is called alone.

Fix this issue by changing nilfs_sufile_resize() to update the range of
allocatable segments immediately after successful truncation of segment
space in case of file system shrink.

Link: https://lkml.kernel.org/r/20230524094348.3784-1-konishi.ryusuke@gmail.com
Fixes: 4e33f9eab07e ("nilfs2: implement resize ioctl")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: syzbot+33494cd0df2ec2931851@syzkaller.appspotmail.com
Closes: https://lkml.kernel.org/r/0000000000005434c405fbbafdc5@google.com
Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
fs/nilfs2/sufile.c