gfs2: Add missing else in trans_add_meta/data (491e94f7) · Commits · 戴 / test

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. Signed-off-by:

Bob Peterson <rpeterso@redhat.com>

fs/gfs2/trans.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -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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