[0/3] btrfs-progs: make convert to generate chunks aligned to stripe boundary

Message

Qu Wenruo Jan. 16, 2024, 3:31 a.m. UTC

There is a recent report about scrub use-after-free, which is caused by
unaligned chunk length (only aligned to sectorsize, but not to
BTRFS_STRIPE_LEN).

Although the bug would soon be fixed in kernel, there is no hard to make
convert to generate data chunks with both start and length aligned to
BTRFS_STRIPE_LEN.

Thankfully the start bytenr is already aligned to 64K, we only need to
make the length aligned.

Furthermore, allow "btrfs check" to detect such unaligned chunks and
gives a warning (but not consider it as an error).
For selftests, we would utilize the debug environment variable,
BTRFS_PROGS_DEBUG_STRICT_CHUNK_ALIGNMENT, to convert the warning to an
error.

Qu Wenruo (3):
  btrfs-progs: convert: make sure the length of data chunks are also
    stripe aligned
  btrfs-progs: add extra chunk alignment checks
  btrfs-progs: tests: enable strict chunk alignment check

 check/common.h       |  1 +
 check/main.c         | 20 ++++++++++++++++++++
 check/mode-lowmem.c  | 11 +++++++++++
 common/utils.c       | 19 +++++++++++++++++++
 common/utils.h       |  1 +
 convert/main.c       |  3 ++-
 tests/common         |  2 ++
 tests/common.convert |  2 ++
 8 files changed, 58 insertions(+), 1 deletion(-)

--
2.43.0

Comments

David Sterba Jan. 16, 2024, 6:16 p.m. UTC | #1

On Tue, Jan 16, 2024 at 02:01:23PM +1030, Qu Wenruo wrote:
> There is a recent report about scrub use-after-free, which is caused by
> unaligned chunk length (only aligned to sectorsize, but not to
> BTRFS_STRIPE_LEN).
> 
> Although the bug would soon be fixed in kernel, there is no hard to make
> convert to generate data chunks with both start and length aligned to
> BTRFS_STRIPE_LEN.
> 
> Thankfully the start bytenr is already aligned to 64K, we only need to
> make the length aligned.
> 
> Furthermore, allow "btrfs check" to detect such unaligned chunks and
> gives a warning (but not consider it as an error).
> For selftests, we would utilize the debug environment variable,
> BTRFS_PROGS_DEBUG_STRICT_CHUNK_ALIGNMENT, to convert the warning to an
> error.
> 
> Qu Wenruo (3):
>   btrfs-progs: convert: make sure the length of data chunks are also
>     stripe aligned
>   btrfs-progs: add extra chunk alignment checks
>   btrfs-progs: tests: enable strict chunk alignment check

Added to devel, with some minor fixups, thanks. The environment variable
name is long but it's just for us and it's descriptive, so OK.