[PATCH] gfs2: gfs2_read_sb: put gfs2_assert inside the loop

[Fox Chen]

for (x = 2;; x++) {
        ...
        gfs2_assert(sdp, x <= GFS2_MAX_META_HEIGHT);  <--- after
        ...
        if (d != sdp->sd_heightsize[x - 1] || m)
                break;
        sdp->sd_heightsize[x] = space;
}

sdp->sd_max_height = x
gfs2_assert(sdp, sdp->sd_max_height <= GFS2_MAX_META_HEIGHT) <--- before

Before this patch, gfs2_assert is put outside of the loop of
sdp->sd_heightsize[x] calculation. When something goes wrong,
x exceeds the size of GFS2_MAX_META_HEIGHT, it may already crash inside
the loop when

sdp->sd_heightsize[x] = space

tries to reach the out-of-bound
location, gfs2_assert won't help here.

This patch fixes this by moving gfs2_assert into the loop.
We will check x value each time to see if it exceeds GFS2_MAX_META_HEIGHT.

Signed-off-by: Fox Chen <foxhlc...@gmail.com>
---
 fs/gfs2/ops_fstype.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index 6d18d2c91add..6cc32e3010f2 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -333,6 +333,7 @@ static int gfs2_read_sb(struct gfs2_sbd *sdp, int silent)
                u64 space, d;
                u32 m;
 
+               gfs2_assert(sdp, x <= GFS2_MAX_META_HEIGHT);
                space = sdp->sd_heightsize[x - 1] * sdp->sd_inptrs;
                d = space;
                m = do_div(d, sdp->sd_inptrs);
@@ -343,7 +344,6 @@ static int gfs2_read_sb(struct gfs2_sbd *sdp, int silent)
        }
        sdp->sd_max_height = x;
        sdp->sd_heightsize[x] = ~0;
-       gfs2_assert(sdp, sdp->sd_max_height <= GFS2_MAX_META_HEIGHT);
 
        sdp->sd_max_dents_per_leaf = (sdp->sd_sb.sb_bsize -
                                      sizeof(struct gfs2_leaf)) /
-- 
2.25.1