Commit 877f919e authored Jun 10, 2018 by Chunyu Hu Committed by Al Viro Jun 27, 2018

proc: add proc_seq_release



kmemleak reported some memory leak on reading proc files. After adding
some debug lines, find that proc_seq_fops is using seq_release as
release handler, which won't handle the free of 'private' field of
seq_file, while in fact the open handler proc_seq_open could create
the private data with __seq_open_private when state_size is greater
than zero. So after reading files created with proc_create_seq_private,
such as /proc/timer_list and /proc/vmallocinfo, the private mem of a
seq_file is not freed. Fix it by adding the paired proc_seq_release
as the default release handler of proc_seq_ops instead of seq_release.

Fixes: 44414d82 ("proc: introduce proc_create_seq_private")
Reviewed-by: Christoph Hellwig <hch@lst.de>
CC: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chunyu Hu <chuhu@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent ce397d21

fs/proc/generic.c

+10 −1

Original line number	Diff line number	Diff line
		@@ -564,11 +564,20 @@ static int proc_seq_open(struct inode inode, struct file file)
		return seq_open(file, de->seq_ops);
		}

		static int proc_seq_release(struct inode inode, struct file file)
		{
		struct proc_dir_entry *de = PDE(inode);

		if (de->state_size)
		return seq_release_private(inode, file);
		return seq_release(inode, file);
		}

		static const struct file_operations proc_seq_fops = {
		.open = proc_seq_open,
		.read = seq_read,
		.llseek = seq_lseek,
		.release = seq_release,
		.release = proc_seq_release,
		};

		struct proc_dir_entry proc_create_seq_private(const char name, umode_t mode,