On Mon, Apr 29, 2024 at 09:01:58AM +0200, Christoph Hellwig wrote:
> Commit a70f9fe52daa ("xfs: detect and handle invalid iclog size set by
> mkfs") added a fixup for incorrect h_size values used for the initial
> umount record in old xfsprogs versions. But it is not using this fixed
> up value to size the log recovery buffer, which can lead to an out of
> bounds access when the incorrect h_size does not come from the old mkfs
> tool, but a fuzzer.
>
> Fix this by open coding xlog_logrec_hblks and taking the fixed h_size
> into account for this calculation.
>
> Fixes: a70f9fe52daa ("xfs: detect and handle invalid iclog size set by mkfs")
> Reported-by: Sam Sun <samsun1006219@xxxxxxxxx>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
The commit log/fixes tag are incorrect... xlog_logrec_hblks() didn't
exist at the time a70f9fe52daa was committed. I suspect this broke later
in commit 0c771b99d6c9 ("xfs: clean up calculation of LR header
blocks"), but please double check.
Otherwise the code changes look fine to me, so with the commit log fixed
up:
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
> fs/xfs/xfs_log_recover.c | 20 ++++++++++++++------
> 1 file changed, 14 insertions(+), 6 deletions(-)
>
> diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
> index b445e8ce4a7d21..bb8957927c3c2e 100644
> --- a/fs/xfs/xfs_log_recover.c
> +++ b/fs/xfs/xfs_log_recover.c
> @@ -2999,7 +2999,7 @@ xlog_do_recovery_pass(
> int error = 0, h_size, h_len;
> int error2 = 0;
> int bblks, split_bblks;
> - int hblks, split_hblks, wrapped_hblks;
> + int hblks = 1, split_hblks, wrapped_hblks;
> int i;
> struct hlist_head rhash[XLOG_RHASH_SIZE];
> LIST_HEAD (buffer_list);
> @@ -3055,14 +3055,22 @@ xlog_do_recovery_pass(
> if (error)
> goto bread_err1;
>
> - hblks = xlog_logrec_hblks(log, rhead);
> - if (hblks != 1) {
> - kvfree(hbp);
> - hbp = xlog_alloc_buffer(log, hblks);
> + /*
> + * This open codes xlog_logrec_hblks so that we can reuse the
> + * fixed up h_size value calculated above. Without that we'd
> + * still allocate the buffer based on the incorrect on-disk
> + * size.
> + */
> + if (h_size > XLOG_HEADER_CYCLE_SIZE &&
> + (rhead->h_version & cpu_to_be32(XLOG_VERSION_2))) {
> + hblks = DIV_ROUND_UP(h_size, XLOG_HEADER_CYCLE_SIZE);
> + if (hblks > 1) {
> + kvfree(hbp);
> + hbp = xlog_alloc_buffer(log, hblks);
> + }
> }
> } else {
> ASSERT(log->l_sectBBsize == 1);
> - hblks = 1;
> hbp = xlog_alloc_buffer(log, 1);
> h_size = XLOG_BIG_RECORD_BSIZE;
> }
> --
> 2.39.2
>
>
