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Mainline Linux tree for various devices, only for fun :)
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Li RongQing 98dfb02aa2 igb: avoid premature Rx buffer reuse 
Igb needs a similar fix as commit 75aab4e10a ("i40e: avoid
premature Rx buffer reuse")

The page recycle code, incorrectly, relied on that a page fragment
could not be freed inside xdp_do_redirect(). This assumption leads to
that page fragments that are used by the stack/XDP redirect can be
reused and overwritten.

To avoid this, store the page count prior invoking xdp_do_redirect().

Longer explanation:

Intel NICs have a recycle mechanism. The main idea is that a page is
split into two parts. One part is owned by the driver, one part might
be owned by someone else, such as the stack.

t0: Page is allocated, and put on the Rx ring
              +---------------
used by NIC ->| upper buffer
(rx_buffer)   +---------------
              | lower buffer
              +---------------
  page count  == USHRT_MAX
  rx_buffer->pagecnt_bias == USHRT_MAX

t1: Buffer is received, and passed to the stack (e.g.)
              +---------------
              | upper buff (skb)
              +---------------
used by NIC ->| lower buffer
(rx_buffer)   +---------------
  page count  == USHRT_MAX
  rx_buffer->pagecnt_bias == USHRT_MAX - 1

t2: Buffer is received, and redirected
              +---------------
              | upper buff (skb)
              +---------------
used by NIC ->| lower buffer
(rx_buffer)   +---------------

Now, prior calling xdp_do_redirect():
  page count  == USHRT_MAX
  rx_buffer->pagecnt_bias == USHRT_MAX - 2

This means that buffer *cannot* be flipped/reused, because the skb is
still using it.

The problem arises when xdp_do_redirect() actually frees the
segment. Then we get:
  page count  == USHRT_MAX - 1
  rx_buffer->pagecnt_bias == USHRT_MAX - 2

From a recycle perspective, the buffer can be flipped and reused,
which means that the skb data area is passed to the Rx HW ring!

To work around this, the page count is stored prior calling
xdp_do_redirect().

Fixes: 9cbc948b5a ("igb: add XDP support")
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Tested-by: Vishakha Jambekar <vishakha.jambekar@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
2021-03-12 08:44:05 -08:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2021-03-10 15:14:56 -08:00
block block/bfq: update comments and default value in docs for fifo_expire 2021-03-02 11:25:38 -07:00
certs certs: Replace K{U,G}IDT_INIT() with GLOBAL_ROOT_{U,G}ID 2021-01-21 16:16:10 +00:00
crypto crypto: mips/poly1305 - enable for all MIPS processors 2021-03-08 11:52:17 +01:00
Documentation Merge git://git.kernel.org:/pub/scm/linux/kernel/git/netdev/net 2021-03-09 17:15:56 -08:00
drivers igb: avoid premature Rx buffer reuse 2021-03-12 08:44:05 -08:00
fs pstore fixes for v5.12-rc2 2021-03-05 17:21:25 -08:00
include net: sched: validate stab values 2021-03-10 15:47:52 -08:00
init kbuild: fix UNUSED_KSYMS_WHITELIST for Clang LTO 2021-02-28 15:19:21 +09:00
ipc fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2021-03-10 15:14:56 -08:00
lib Merge git://git.kernel.org:/pub/scm/linux/kernel/git/davem/sparc 2021-03-08 22:01:58 -08:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
mm swap: fix swapfile read/write offset 2021-03-02 17:25:46 -07:00
net net: sock: simplify tw proto registration 2021-03-11 16:05:08 -08:00
samples Merge git://git.kernel.org:/pub/scm/linux/kernel/git/netdev/net 2021-03-09 17:15:56 -08:00
scripts gcc-plugins fixes for v5.12-rc2 2021-03-05 17:23:03 -08:00
security Keyrings miscellany 2021-02-23 16:09:23 -08:00
sound ALSA: hda/realtek: Apply dual codec quirks for MSI Godlike X570 board 2021-03-03 15:25:03 +01:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2021-03-10 15:14:56 -08:00
usr Kbuild updates for v5.12 2021-02-25 10:17:31 -08:00
virt KVM: x86/mmu: Consider the hva in mmu_notifier retry 2021-02-22 13:16:53 -05:00
.clang-format cxl for 5.12 2021-02-24 09:38:36 -08:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore clang-lto series for v5.12-rc1 2021-02-23 09:28:51 -08:00
.mailmap treewide: Miguel has moved 2021-02-26 09:41:03 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS treewide: Miguel has moved 2021-02-26 09:41:03 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Merge git://git.kernel.org:/pub/scm/linux/kernel/git/netdev/net 2021-03-09 17:15:56 -08:00
Makefile Linux 5.12-rc2 2021-03-05 17:33:41 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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 Restructured Text 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.