Re: [PATCH] xfs_logprint: fix pointer bug

["Darrick J. Wong" <djwong@kernel.org>]

On Wed, Dec 10, 2025 at 12:10:08PM +0100, Andrey Albershteyn wrote:
> On 2025-12-09 12:57:38, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@kernel.org>
> > 
> > generic/055 captures a crash in xfs_logprint due to an incorrect
> > refactoring trying to increment a pointer-to-pointer whereas before it
> > incremented a pointer.
> > 
> > Fixes: 5a9b7e95140893 ("logprint: factor out a xlog_print_op helper")
> > Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
> > ---
> >  logprint/log_misc.c |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/logprint/log_misc.c b/logprint/log_misc.c
> > index 16353ebd728f35..8e0589c161b871 100644
> > --- a/logprint/log_misc.c
> > +++ b/logprint/log_misc.c
> > @@ -992,7 +992,7 @@ xlog_print_op(
> >  			printf("0x%02x ", (unsigned int)**ptr);
> >  			if (n % 16 == 15)
> >  				printf("\n");
> > -			ptr++;
> > +			(*ptr)++;
> >  		}
> >  		printf("\n");
> >  		return true;
> > 
> 
> Hmm, checking the results I also see the segfauls in 055.full but
> test is passing. Is there any xfstests setting to make it fail on
> coredumps/segfaults?

Well in theory it already captures coredumps ... if they're named "core"
and get written to $here.  But then coredumpctl intervenes and whisks
them all away so fstests never sees them.

Starting Nov 2025, fstests can query coredumps from systemd:
https://git.kernel.org/pub/scm/fs/xfs/xfstests-dev.git/commit/?id=9886baabdec372387b5e874fdcaf59390a75f4a9

though obviously this isn't compatible with check-parallel because
there's no good way to tag a process tree for coredumpctl so that you
can query dumps only from that tree later.

--D

> -- 
> - Andrey
> 
>