* [Cluster-devel] [GFS2 PATCH] gfs2: Add missing else in trans_add_meta/data
[not found] <1226969049.38347148.1443718728281.JavaMail.zimbra@redhat.com>
@ 2015-10-01 17:00 ` Bob Peterson
0 siblings, 0 replies; only message in thread
From: Bob Peterson @ 2015-10-01 17:00 UTC (permalink / raw)
To: cluster-devel.redhat.com
Hi,
This patch fixes a timing window that causes a segfault.
The problem is that bd can remain NULL throughout the function
and then reference that NULL pointer if the bh->b_private starts
out NULL, then someone sets it to non-NULL inside the locking.
In that case, bd still needs to be set.
Regards,
Bob Peterson
Red Hat File Systems
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
---
fs/gfs2/trans.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/fs/gfs2/trans.c b/fs/gfs2/trans.c
index b95d0d6..0c1bde3 100644
--- a/fs/gfs2/trans.c
+++ b/fs/gfs2/trans.c
@@ -176,6 +176,8 @@ void gfs2_trans_add_data(struct gfs2_glock *gl, struct buffer_head *bh)
unlock_buffer(bh);
if (bh->b_private == NULL)
bd = gfs2_alloc_bufdata(gl, bh, &gfs2_databuf_lops);
+ else
+ bd = bh->b_private;
lock_buffer(bh);
gfs2_log_lock(sdp);
}
@@ -236,6 +238,8 @@ void gfs2_trans_add_meta(struct gfs2_glock *gl, struct buffer_head *bh)
lock_page(bh->b_page);
if (bh->b_private == NULL)
bd = gfs2_alloc_bufdata(gl, bh, &gfs2_buf_lops);
+ else
+ bd = bh->b_private;
unlock_page(bh->b_page);
lock_buffer(bh);
gfs2_log_lock(sdp);
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