[PATCH 5.15 012/124] gfs2: assign rgrp glock before compute_bitstructs

Greg Kroah-Hartman
2022-04-26T08:58:36Z

From: Bob Peterson <rpeterso@redhat.com>

commit 428f651cb80b227af47fc302e4931791f2fb4741 upstream.

Before this patch, function read_rindex_entry called compute_bitstructs
before it allocated a glock for the rgrp. But if compute_bitstructs found
a problem with the rgrp, it called gfs2_consist_rgrpd, and that called
gfs2_dump_glock for rgd->rd_gl which had not yet been assigned.

read_rindex_entry
compute_bitstructs
gfs2_consist_rgrpd
gfs2_dump_glock <---------rgd->rd_gl was not set.

This patch changes read_rindex_entry so it assigns an rgrp glock before
calling compute_bitstructs so gfs2_dump_glock does not reference an
unassigned pointer. If an error is discovered, the glock must also be
put, so a new goto and label were added.

Reported-by: syzbot+c6fd14145e2f62ca0784@syzkaller.appspotmail.com
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/gfs2/rgrp.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -923,15 +923,15 @@ static int read_rindex_entry(struct gfs2
spin_lock_init(&rgd->rd_rsspin);
mutex_init(&rgd->rd_mutex);

- error = compute_bitstructs(rgd);
- if (error)
- goto fail;
-
error = gfs2_glock_get(sdp, rgd->rd_addr,
&gfs2_rgrp_glops, CREATE, &rgd->rd_gl);
if (error)
goto fail;

+ error = compute_bitstructs(rgd);
+ if (error)
+ goto fail_glock;
+
rgd->rd_rgl = (struct gfs2_rgrp_lvb *)rgd->rd_gl->gl_lksb.sb_lvbptr;
rgd->rd_flags &= ~(GFS2_RDF_UPTODATE | GFS2_RDF_PREFERRED);
if (rgd->rd_data > sdp->sd_max_rg_data)
@@ -945,6 +945,7 @@ static int read_rindex_entry(struct gfs2
}

error = 0; /* someone else read in the rgrp; free it and ignore it */
+fail_glock:
gfs2_glock_put(rgd->rd_gl);