From: Bob Peterson <rpeterso@xxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Bob Peterson <rpeterso@xxxxxxxxxx> Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/gfs2/rgrp.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) --- a/fs/gfs2/rgrp.c +++ b/fs/gfs2/rgrp.c @@ -917,15 +917,15 @@ static int read_rindex_entry(struct gfs2 rgd->rd_bitbytes = be32_to_cpu(buf.ri_bitbytes); spin_lock_init(&rgd->rd_rsspin); - 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) @@ -942,6 +942,7 @@ 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); fail: Patches currently in stable-queue which might be from rpeterso@xxxxxxxxxx are queue-4.9/gfs2-assign-rgrp-glock-before-compute_bitstructs.patch