From: Bob Peterson <rpeterso@redhat.com> commit 778721510e84209f78e31e2ccb296ae36d623f5e upstream. If gfs2 tries to mount a (corrupt) file system that has no resource groups it still tries to set preferences on the first one, which causes a kernel null pointer dereference. This patch adds a check to function gfs2_ri_update so this condition is detected and reported back as an error. Reported-by: syzbot+e3f23ce40269a4c9053a@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> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- fs/gfs2/rgrp.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c index de9b561b1c38..054fdfd4fb8b 100644 --- a/fs/gfs2/rgrp.c +++ b/fs/gfs2/rgrp.c @@ -1009,6 +1009,10 @@ static int gfs2_ri_update(struct gfs2_inode *ip) if (error < 0) return error; + if (RB_EMPTY_ROOT(&sdp->sd_rindex_tree)) { + fs_err(sdp, "no resource groups found in the file system.\n"); + return -ENOENT; + } set_rgrp_preferences(sdp); sdp->sd_rindex_uptodate = 1; -- 2.25.1