staging: lustre: Don't leak 'buffer' in cfs_get_environ()

If 'down_read_trylock' fails we'll curently leak the memory allocated to 'buffer'.
Fix the leak by simply kfree'ing 'buffer' before returning '-EDEADLK'.
Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/libcfs/linux/linux-curproc.c

@@ -227,8 +227,10 @@ int cfs_get_environ(const char *key, char *value, int *val_len)
 	 * which is already holding mmap_sem for writes.  If some other
 	 * thread gets the write lock in the meantime, this thread will
 	 * block, but at least it won't deadlock on itself.  LU-1735 */
-	if (down_read_trylock(&mm->mmap_sem) == 0)
+	if (down_read_trylock(&mm->mmap_sem) == 0) {
+		kfree(buffer);
 		return -EDEADLK;
+	}
 	up_read(&mm->mmap_sem);
 
 	addr = mm->env_start;