Re: [PATCH v3] pipe: Fix memory leaks in create_pipe_files()

[Al Viro]

On Thu, Oct 01, 2020 at 08:50:55AM -0400, Qian Cai wrote:
> Calling pipe2() with O_NOTIFICATION_PIPE could results in memory leaks
> in an error path or CONFIG_WATCH_QUEUE=n. Plug them.

[snip the copy of bug report]

No objections on the patch itself, but commit message is just about
unreadable.  How about something along the lines of the following?

=======================
	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 c73be61cede5 ("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 wath_queue_init() in !CONFIG_WATCH_QUEUE
case and by having failures of wath_queue_init() handled the same way
we handle alloc_file_pseudo() ones.

Fixes: c73be61cede5 ("pipe: Add general notification queue support")
Signed-off-by: Qian Cai <cai@xxxxxxxxxx>
=======================