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authorMasatake YAMATO <yamato@redhat.com>2012-06-18 16:31:31 +0900
committerSteven Whitehouse <swhiteho@redhat.com>2012-06-28 15:35:47 +0100
commit44b8db13860a449b5d85afdc65da654ce56da678 (patch)
tree1487b0bb967086607e50ce51a98eb1613b375b03
parent666d1d8ad201803862514317c17695925e61316b (diff)
GFS2: Fixing double brelse'ing bh allocated in gfs2_meta_read when EIO occurs
This patch fixes buffer_head double free in following code path: gfs2_block_map => gfs2_meta_inode_buffer => gfs2_meta_indirect_buffer => gfs2_meta_read => release_metapath gfs2_block_map calls gfs2_meta_inode_buffer with &mp.mp_bh[0] as an argument. mp.mp_bh are filled with zero at the beginning of gfs2_block_map. If gfs2_meta_inode_buffer returns non-zero value, gfs2_block_map calls release_metapath to free buffers chained to mp.mp_bh. release_metapath checks each slot of mp.mp_bh[i] and free(with brelse) unless the slot is filled with NULL. &mp.mp_bh[0] passed to gfs2_meta_inode_buffer is filled at gfs2_meta_read. gfs2_meta_read is filled a buffer allocated with gfs2_getbuf even if EIO occurs. When EIO occurs, the allocated buffer is brelse'ed though the pointer(wrong poiner) points the brelse'ed is passed back to caller via an argument bhp. gfs2_meta_indirect_buffer, the caller also pass the wrong pointer to its caller with EIO. Finally gfs2_block_map gets both EIO and &mp.mp_bh[0] filled with the wrong pointer. release_metapath calls brelse again on the wrong pointer. Signed-off-by: Masatake YAMATO <yamato@redhat.com> Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
-rw-r--r--fs/gfs2/meta_io.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/fs/gfs2/meta_io.c b/fs/gfs2/meta_io.c
index 6c1e5d1c404a..3a56c8d94de0 100644
--- a/fs/gfs2/meta_io.c
+++ b/fs/gfs2/meta_io.c
@@ -213,8 +213,10 @@ int gfs2_meta_read(struct gfs2_glock *gl, u64 blkno, int flags,
struct gfs2_sbd *sdp = gl->gl_sbd;
struct buffer_head *bh;
- if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
+ if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {
+ *bhp = NULL;
return -EIO;
+ }
*bhp = bh = gfs2_getbuf(gl, blkno, CREATE);
@@ -235,6 +237,7 @@ int gfs2_meta_read(struct gfs2_glock *gl, u64 blkno, int flags,
if (tr && tr->tr_touched)
gfs2_io_error_bh(sdp, bh);
brelse(bh);
+ *bhp = NULL;
return -EIO;
}