Commit 8a018eb5 authored Oct 01, 2020 by Qian Cai Committed by Al Viro Oct 01, 2020

pipe: Fix memory leaks in create_pipe_files()



        Calling pipe2() with O_NOTIFICATION_PIPE could results in memory
leaks unless watch_queue_init() is successful.

        In case of watch_queue_init() failure in pipe2() we are left
with inode and pipe_inode_info instances that need to be freed.  That
failure exit has been introduced in commit c73be61c ("pipe: Add
general notification queue support") and its handling should've been
identical to nearby treatment of alloc_file_pseudo() failures - it
is dealing with the same situation.  As it is, the mainline kernel
leaks in that case.

        Another problem is that CONFIG_WATCH_QUEUE and !CONFIG_WATCH_QUEUE
cases are treated differently (and the former leaks just pipe_inode_info,
the latter - both pipe_inode_info and inode).

        Fixed by providing a dummy wacth_queue_init() in !CONFIG_WATCH_QUEUE
case and by having failures of wacth_queue_init() handled the same way
we handle alloc_file_pseudo() ones.

Fixes: c73be61c ("pipe: Add general notification queue support")
Signed-off-by: Qian Cai <cai@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent 933a3752

fs/pipe.c

+5 −6

Original line number	Diff line number	Diff line
		@@ -913,19 +913,18 @@ int create_pipe_files(struct file **res, int flags)
		{
		struct inode *inode = get_pipe_inode();
		struct file *f;
		int error;

		if (!inode)
		return -ENFILE;

		if (flags & O_NOTIFICATION_PIPE) {
		#ifdef CONFIG_WATCH_QUEUE
		if (watch_queue_init(inode->i_pipe) < 0) {
		error = watch_queue_init(inode->i_pipe);
		if (error) {
		free_pipe_info(inode->i_pipe);
		iput(inode);
		return -ENOMEM;
		return error;
		}
		#else
		return -ENOPKG;
		#endif
		}

		f = alloc_file_pseudo(inode, pipe_mnt, "",

include/linux/watch_queue.h

+6 −0

Original line number	Diff line number	Diff line
		@@ -122,6 +122,12 @@ static inline void remove_watch_list(struct watch_list *wlist, u64 id)
		*/
		#define watch_sizeof(STRUCT) (sizeof(STRUCT) << WATCH_INFO_LENGTH__SHIFT)

		#else
		static inline int watch_queue_init(struct pipe_inode_info *pipe)
		{
		return -ENOPKG;
		}

		#endif

		#endif /* _LINUX_WATCH_QUEUE_H */

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