Re: [PATCH 0/5] ext4/overlayfs: fiemap related fixes

[Murphy Zhou <jencce.kernel@gmail.com>]

On Thu, Apr 23, 2020 at 04:17:52PM +0530, Ritesh Harjani wrote:
> Hello All,
> 
> Here are some changes, which as I understand, takes the right approach in fixing
> the offset/length bounds check problem reported in threads [1]-[2].
> These warnings in iomap_apply/ext4 path are reported after ext4_fiemap()
> was moved to use iomap framework and when overlayfs is mounted on top of ext4.
> Though the issues were identified after ext4 moved to iomap framework, but
> these changes tries to fix the problem which are anyways present in current code
> irrespective of ext4 using iomap framework for fiemap or not.

Ping?

> 
> Patch 1 & 4 commit msg may give more details of the problem.
> 
> Tests done
> ==========
> 1. Tested xfstest-suite with "-g quick" & "-overlay -g quick" configuration
> on a 4k blocksize on x86 & Power. There were no new failures reported
> due to these changes.
> 2. Tested syzcaller reported problem with this change. [1]
> 3. Tested below change which was reported by Murphy. [2]
> 	The minimal reproducer is:
> 	-------------------------------------
> 	fallocate -l 256M test.img
> 	mkfs.ext4 -Fq -b 4096 -I 256 test.img
> 	mkdir -p test
> 	mount -o loop test.img test || exit
> 	pushd test
> 	rm -rf l u w m
> 	mkdir -p l u w m
> 	mount -t overlay -o lowerdir=l,upperdir=u,workdir=w overlay m || exit
> 	xfs_io -f -c "pwrite 0 4096" -c "fiemap"  m/tf
> 	umount m
> 	rm -rf l u w m
> 	popd
> 	umount -d test
> 	rm -rf test test.img
> 	-------------------------------------
> 
> Comments/feedback are much welcome!!
> 
> References
> ==========
> [1]: https://lkml.org/lkml/2020/4/11/46
> [2]: https://patchwork.ozlabs.org/project/linux-ext4/patch/20200418233231.z767yvfiupy7hwgp@xzhoux.usersys.redhat.com/ 
> 
> 
> Ritesh Harjani (5):
>   ext4: Fix EXT4_MAX_LOGICAL_BLOCK macro
>   ext4: Rename fiemap_check_ranges() to make it ext4 specific
>   vfs: EXPORT_SYMBOL for fiemap_check_ranges()
>   overlayfs: Check for range bounds before calling i_op->fiemap()
>   ext4: Get rid of ext4_fiemap_check_ranges
> 
>  fs/ext4/ext4.h       |  2 +-
>  fs/ext4/ioctl.c      | 23 -----------------------
>  fs/ioctl.c           |  5 +++--
>  fs/overlayfs/inode.c |  7 ++++++-
>  include/linux/fs.h   |  2 ++
>  5 files changed, 12 insertions(+), 27 deletions(-)
> 
> -- 
> 2.21.0
> 

-- 
Murphy