kernel/linux
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ synced 2026-11-08 18:57:22 +00:00
Code Issues Releases Packages Activity
No description
1,321,127 commits 117 branches 5,824 tags 6.2 GiB
  • C 96.8%
  • Assembly 0.9%
  • Rust 0.7%
  • Shell 0.6%
  • Python 0.5%
  • Other 0.3%
Find a file
Dominique Martinet 4652d0b6f7 iov_iter: iterate_folioq: fix handling of offset >= folio size 
commit 808471ddb0 upstream.

It's apparently possible to get an iov advanced all the way up to the end
of the current page we're looking at, e.g.

(gdb) p *iter
$24 = {iter_type = 4 '\004', nofault = false, data_source = false, iov_offset = 4096, {__ubuf_iovec = {
      iov_base = 0xffff88800f5bc000, iov_len = 655}, {{__iov = 0xffff88800f5bc000, kvec = 0xffff88800f5bc000,
        bvec = 0xffff88800f5bc000, folioq = 0xffff88800f5bc000, xarray = 0xffff88800f5bc000,
        ubuf = 0xffff88800f5bc000}, count = 655}}, {nr_segs = 2, folioq_slot = 2 '\002', xarray_start = 2}}

Where iov_offset is 4k with 4k-sized folios

This should have been fine because we're only in the 2nd slot and there's
another one after this, but iterate_folioq should not try to map a folio
that skips the whole size, and more importantly part here does not end up
zero (because 'PAGE_SIZE - skip % PAGE_SIZE' ends up PAGE_SIZE and not
zero..), so skip forward to the "advance to next folio" code

Link: https://lkml.kernel.org/r/20250813-iot_iter_folio-v3-0-a0ffad2b665a@codewreck.org
Link: https://lkml.kernel.org/r/20250813-iot_iter_folio-v3-1-a0ffad2b665a@codewreck.org
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Fixes: db0aa2e956 ("mm: Define struct folio_queue and ITER_FOLIOQ to handle a sequence of folios")
Reported-by: Maximilian Bosch <maximilian@mbosch.me>
Reported-by: Ryan Lahfa <ryan@lahfa.xyz>
Reported-by: Christian Theune <ct@flyingcircus.io>
Reported-by: Arnout Engelen <arnout@bzzt.net>
Link: https://lkml.kernel.org/r/D4LHHUNLG79Y.12PI0X6BEHRHW@mbosch.me/
Acked-by: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: <stable@vger.kernel.org>	[6.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2025-08-28 16:31:05 +02:00
arch
block
certs
crypto
Documentation
drivers
fs
include
init
io_uring
ipc
kernel
lib
LICENSES
mm
net
rust
samples
scripts
security
sound
tools
usr
virt
.clang-format
.clippy.toml
.cocciconfig
.editorconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
.rustfmt.toml
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile
README

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.