Description of problem:

fsck.gfs2 crashes with a segmentation fault when sb_bsize is corrupted in the on-disk superblock.

Version-Release number of selected component (if applicable):

Upstream git

How reproducible:

100%

Steps to Reproduce:

# truncate -s 10G tdev
# mkfs.gfs2 -Oplock_nolock tdev
# gfs2_edit -p sb field sb_bsize 0 ./tdev
# fsck.gfs2 tdev

Actual results:

# fsck.gfs2 tdev
Initializing fsck
Segmentation fault (core dumped)

Expected results:

fsck.gfs2 either fixes the superblock or prints a message saying that fsck.gfs2 could not fix it before exiting cleanly.

Additional info:

Program received signal SIGSEGV, Segmentation fault.
0x00000000004292ef in read_sb (sdp=0x7fffffffbe70) at super.c:97
97			sdp->sd_heightsize[x] = space;
Missing separate debuginfos, use: debuginfo-install glibc-2.17-33.el7.x86_64
(gdb) bt
#0  0x00000000004292ef in read_sb (sdp=0x7fffffffbe70) at super.c:97
#1  0x000000000040761e in fill_super_block (sdp=0x7fffffffbe70) at initialize.c:1276
#2  0x0000000000407f53 in initialize (sdp=0x7fffffffbe70, force_check=0, preen=0, all_clean=0x7fffffffbe6c)
    at initialize.c:1520
#3  0x000000000040ae49 in main (argc=2, argv=0x7fffffffe4a8) at main.c:283
(gdb) list
92			space = sdp->sd_heightsize[x - 1] * sdp->sd_inptrs;
93			/* FIXME: Do we really need this first check?? */
94			if (space / sdp->sd_inptrs != sdp->sd_heightsize[x - 1] ||
95			    space % sdp->sd_inptrs != 0)
96				break;
97			sdp->sd_heightsize[x] = space;
98		}
99		if (x > GFS2_MAX_META_HEIGHT){
100			errno = E2BIG;
101			return -1;