tree a2e80e19f07b38271ee918a8463ea453c50bb256
parent 36c281e0b32d6297153e716451e8f157f863af72
author Changwei Ge <ge.changwei@h3c.com> 1530693750 +0200
committer Michal Hocko <mhocko@suse.com> 1530693750 +0200

ocfs2: don't put and assigning null to bh allocated outside

ocfs2_read_blocks() and ocfs2_read_blocks_sync() are both used to read
several blocks from disk.  Currently, the input argument *bhs* can be NULL
or NOT.  It depends on the caller's behavior.  If the function fails in
reading blocks from disk, the corresponding bh will be assigned to NULL
and put.

Obviously, above process for non-NULL input bh is not appropriate.
Because the caller doesn't even know its bhs are put and re-assigned.

If buffer head is managed by caller, ocfs2_read_blocks and
ocfs2_read_blocks_sync() should not evaluate it to NULL.  It will cause
caller accessing illegal memory, thus crash.

Link: http://lkml.kernel.org/r/HK2PR06MB045285E0F4FBB561F9F2F9B3D5680@HK2PR06MB0452.apcprd06.prod.outlook.com
Signed-off-by: Changwei Ge <ge.changwei@h3c.com>
Reviewed-by: Guozhonghua <guozhonghua@h3c.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <jiangqi903@gmail.com>
Cc: Changwei Ge <ge.changwei@h3c.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>