On Wed, Aug 21, 2024 at 06:44:12PM +0800, liuhuan01@xxxxxxxxxx wrote:
> From: liuh <liuhuan01@xxxxxxxxxx>
>
> Recently, I was testing xfstests. When I run xfs/350 case, it always generate coredump during the process.
> xfs_db -c "sb 0" -c "p agblocks" /dev/loop1
>
> System will generate signal SIGFPE corrupt the process. And the stack as follow:
> corrupt at: (*bpp)->b_pag = xfs_perag_get(btp->bt_mount, xfs_daddr_to_agno(btp->bt_mount, blkno)); in function libxfs_getbuf_flags
> #0 libxfs_getbuf_flags
> #1 libxfs_getbuf_flags
> #2 libxfs_buf_read_map
> #3 libxfs_buf_read
> #4 libxfs_mount
> #5 init
> #6 main
>
> The coredump was caused by the corrupt superblock metadata: (mp)->m_sb.sb_agblocks, it was 0.
> In this case, user cannot run in expert mode also.
>
> Never check (mp)->m_sb.sb_agblocks before use it cause this issue.
> Make sure (mp)->m_sb.sb_agblocks > 0 before libxfs_mount to prevent corruption and leave a message.
>
> Signed-off-by: liuh <liuhuan01@xxxxxxxxxx>
> ---
> db/init.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/db/init.c b/db/init.c
> index cea25ae5..2d3295ba 100644
> --- a/db/init.c
> +++ b/db/init.c
> @@ -129,6 +129,13 @@ init(
> }
> }
>
> + if (unlikely(sbp->sb_agblocks == 0)) {
> + fprintf(stderr,
> + _("%s: device %s agblocks unexpected\n"),
> + progname, x.data.name);
> + exit(1);
What if we set sb_agblocks to 1 and let the debugger continue?
--D
> + }
> +
> agcount = sbp->sb_agcount;
> mp = libxfs_mount(&xmount, sbp, &x, LIBXFS_MOUNT_DEBUGGER);
> if (!mp) {
> --
> 2.43.0
>
