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Mohamed Khalfella 2ea35288c8 skbuff: skb_segment, Call zero copy functions before using skbuff frags Commit `bf5c25d608` ("skbuff: in skb_segment, call zerocopy functions once per nskb") added the call to zero copy functions in skb_segment(). The change introduced a bug in skb_segment() because skb_orphan_frags() may possibly change the number of fragments or allocate new fragments altogether leaving nrfrags and frag to point to the old values. This can cause a panic with stacktrace like the one below. [ 193.894380] BUG: kernel NULL pointer dereference, address: 00000000000000bc [ 193.895273] CPU: 13 PID: 18164 Comm: vh-net-17428 Kdump: loaded Tainted: G O 5.15.123+ #26 [ 193.903919] RIP: 0010:skb_segment+0xb0e/0x12f0 [ 194.021892] Call Trace: [ 194.027422] <TASK> [ 194.072861] tcp_gso_segment+0x107/0x540 [ 194.082031] inet_gso_segment+0x15c/0x3d0 [ 194.090783] skb_mac_gso_segment+0x9f/0x110 [ 194.095016] __skb_gso_segment+0xc1/0x190 [ 194.103131] netem_enqueue+0x290/0xb10 [sch_netem] [ 194.107071] dev_qdisc_enqueue+0x16/0x70 [ 194.110884] __dev_queue_xmit+0x63b/0xb30 [ 194.121670] bond_start_xmit+0x159/0x380 [bonding] [ 194.128506] dev_hard_start_xmit+0xc3/0x1e0 [ 194.131787] __dev_queue_xmit+0x8a0/0xb30 [ 194.138225] macvlan_start_xmit+0x4f/0x100 [macvlan] [ 194.141477] dev_hard_start_xmit+0xc3/0x1e0 [ 194.144622] sch_direct_xmit+0xe3/0x280 [ 194.147748] __dev_queue_xmit+0x54a/0xb30 [ 194.154131] tap_get_user+0x2a8/0x9c0 [tap] [ 194.157358] tap_sendmsg+0x52/0x8e0 [tap] [ 194.167049] handle_tx_zerocopy+0x14e/0x4c0 [vhost_net] [ 194.173631] handle_tx+0xcd/0xe0 [vhost_net] [ 194.176959] vhost_worker+0x76/0xb0 [vhost] [ 194.183667] kthread+0x118/0x140 [ 194.190358] ret_from_fork+0x1f/0x30 [ 194.193670] </TASK> In this case calling skb_orphan_frags() updated nr_frags leaving nrfrags local variable in skb_segment() stale. This resulted in the code hitting i >= nrfrags prematurely and trying to move to next frag_skb using list_skb pointer, which was NULL, and caused kernel panic. Move the call to zero copy functions before using frags and nr_frags. Fixes: `bf5c25d608` ("skbuff: in skb_segment, call zerocopy functions once per nskb") Signed-off-by: Mohamed Khalfella <mkhalfella@purestorage.com> Reported-by: Amit Goyal <agoyal@purestorage.com> Cc: stable@vger.kernel.org Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2023-09-01 08:09:07 +01:00
Documentation	bpf-for-netdev	2023-08-31 18:44:24 -07:00
LICENSES	LICENSES: Add the copyleft-next-0.3.1 license	2022-11-08 15:44:01 +01:00
arch	Networking changes for 6.6.	2023-08-29 11:33:01 -07:00
block	v6.6-vfs.super	2023-08-28 11:04:18 -07:00
certs	certs: Reference revocation list for all keyrings	2023-08-17 20:12:41 +00:00
crypto	This update includes the following changes:	2023-08-29 11:23:29 -07:00
drivers	NFC: nxp: add NXP1002	2023-08-30 18:32:24 -07:00
fs	pstore updates for v6.6-rc1	2023-08-28 12:36:04 -07:00
include	net: annotate data-races around sk->sk_tsflags	2023-09-01 07:27:33 +01:00
init	Scheduler changes for v6.6:	2023-08-28 16:43:39 -07:00
io_uring	New code for 6.6:	2023-08-28 11:59:52 -07:00
ipc	mqueue: convert to ctime accessor functions	2023-07-24 10:30:07 +02:00
kernel	netfilter: nf_tables: Audit log rule reset	2023-08-31 01:29:28 +02:00
lib	Networking changes for 6.6.	2023-08-29 11:33:01 -07:00
mm	Networking changes for 6.6.	2023-08-29 11:33:01 -07:00
net	skbuff: skb_segment, Call zero copy functions before using skbuff frags	2023-09-01 08:09:07 +01:00
rust	Rust changes for v6.6	2023-08-29 08:19:46 -07:00
samples	Networking changes for 6.6.	2023-08-29 11:33:01 -07:00
scripts	bpf, docs: Fix invalid escape sequence warnings in bpf_doc.py	2023-08-31 13:56:31 +02:00
security	Networking changes for 6.6.	2023-08-29 11:33:01 -07:00
sound	regmap: Updates for v6.6	2023-08-29 09:26:04 -07:00
tools	selftests/bpf: Include build flavors for install target	2023-08-31 22:01:53 +02:00
usr	initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP	2023-06-06 17:54:49 +09:00
virt	KVM: Grab a reference to KVM for VM and vCPU stats file descriptors	2023-07-29 11:05:28 -04:00
.clang-format	iommu: Add for_each_group_device()	2023-05-23 08:15:51 +02:00
.cocciconfig	…
.get_maintainer.ignore	get_maintainer: add Alan to .get_maintainer.ignore	2022-08-20 15:17:44 -07:00
.gitattributes	.gitattributes: set diff driver for Rust source code files	2023-05-31 17:48:25 +02:00
.gitignore	Revert ".gitignore: ignore .cover and .mbx"	2023-07-04 15:05:12 -07:00
.mailmap	mailmap: add entries for Simon Horman	2023-08-16 09:53:10 +01:00
.rustfmt.toml	rust: add `.rustfmt.toml`	2022-09-28 09:02:20 +02:00
COPYING	COPYING: state that all contributions really are covered by this file	2020-02-10 13:32:20 -08:00
CREDITS	- Address -Wmissing-prototype warnings	2023-06-26 16:43:54 -07:00
Kbuild	Kbuild updates for v6.1	2022-10-10 12:00:45 -07:00
Kconfig	kbuild: ensure full rebuild when the compiler is updated	2020-05-12 13:28:33 +09:00
MAINTAINERS	Networking changes for 6.6.	2023-08-29 11:33:01 -07:00
Makefile	Rust changes for v6.6	2023-08-29 08:19:46 -07:00
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.