linux-kernel - [PATCH 0/2] pipe: change pipe_write() to never add a zero-sized buffer

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250209150718.GA17013@redhat.com>
Date: Sun, 9 Feb 2025 16:07:18 +0100
From: Oleg Nesterov <oleg@...hat.com>
To: Christian Brauner <brauner@...nel.org>,
	Jeff Layton <jlayton@...nel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Cc: David Howells <dhowells@...hat.com>,
	"Gautham R. Shenoy" <gautham.shenoy@....com>,
	K Prateek Nayak <kprateek.nayak@....com>,
	Mateusz Guzik <mjguzik@...il.com>,
	Neeraj Upadhyay <Neeraj.Upadhyay@....com>,
	Oliver Sang <oliver.sang@...el.com>,
	Swapnil Sapkal <swapnil.sapkal@....com>,
	WangYuli <wangyuli@...ontech.com>, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 0/2] pipe: change pipe_write() to never add a zero-sized
 buffer

Please review.

pipe_write() can insert the empty buffer and this looks very confusing
to me. Because it looks obviously unnecessary and complicates the code.

In fact this logic doesn't even look strictly correct. For example,
eat_empty_buffer() simply updates pipe->tail but (unlike pipe_read) it
doesn't wake the writers.

But is pipe_write() is the only possible source of buf->len == 0 ?
I am not 100% sure, fs/splice.c is very nontrivial, but it seems that
this code at least tries to not add a zero-sized buf into pipe->bufs.

Oleg.
---

 fs/pipe.c                 | 47 ++++++++++-------------------------------------
 fs/splice.c               | 14 ++++++--------
 include/linux/pipe_fs_i.h |  6 ++++++
 3 files changed, 22 insertions(+), 45 deletions(-)