kernel/linux
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ synced 2026-10-16 22:39:48 +00:00
Code Issues Releases Packages Activity
No description
1,122,841 commits 116 branches 5,798 tags 5.6 GiB
  • C 96.9%
  • Assembly 0.9%
  • Rust 0.6%
  • Shell 0.6%
  • Python 0.5%
  • Other 0.3%
Find a file
Vladimir Oltean db46e3a88a net/sched: taprio: avoid disabling offload when it was never enabled 
In an incredibly strange API design decision, qdisc->destroy() gets
called even if qdisc->init() never succeeded, not exclusively since
commit 87b60cfacf ("net_sched: fix error recovery at qdisc creation"),
but apparently also earlier (in the case of qdisc_create_dflt()).

The taprio qdisc does not fully acknowledge this when it attempts full
offload, because it starts off with q->flags = TAPRIO_FLAGS_INVALID in
taprio_init(), then it replaces q->flags with TCA_TAPRIO_ATTR_FLAGS
parsed from netlink (in taprio_change(), tail called from taprio_init()).

But in taprio_destroy(), we call taprio_disable_offload(), and this
determines what to do based on FULL_OFFLOAD_IS_ENABLED(q->flags).

But looking at the implementation of FULL_OFFLOAD_IS_ENABLED()
(a bitwise check of bit 1 in q->flags), it is invalid to call this macro
on q->flags when it contains TAPRIO_FLAGS_INVALID, because that is set
to U32_MAX, and therefore FULL_OFFLOAD_IS_ENABLED() will return true on
an invalid set of flags.

As a result, it is possible to crash the kernel if user space forces an
error between setting q->flags = TAPRIO_FLAGS_INVALID, and the calling
of taprio_enable_offload(). This is because drivers do not expect the
offload to be disabled when it was never enabled.

The error that we force here is to attach taprio as a non-root qdisc,
but instead as child of an mqprio root qdisc:

$ tc qdisc add dev swp0 root handle 1: \
	mqprio num_tc 8 map 0 1 2 3 4 5 6 7 \
	queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 hw 0
$ tc qdisc replace dev swp0 parent 1:1 \
	taprio num_tc 8 map 0 1 2 3 4 5 6 7 \
	queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 base-time 0 \
	sched-entry S 0x7f 990000 sched-entry S 0x80 100000 \
	flags 0x0 clockid CLOCK_TAI
Unable to handle kernel paging request at virtual address fffffffffffffff8
[fffffffffffffff8] pgd=0000000000000000, p4d=0000000000000000
Internal error: Oops: 96000004 [#1] PREEMPT SMP
Call trace:
 taprio_dump+0x27c/0x310
 vsc9959_port_setup_tc+0x1f4/0x460
 felix_port_setup_tc+0x24/0x3c
 dsa_slave_setup_tc+0x54/0x27c
 taprio_disable_offload.isra.0+0x58/0xe0
 taprio_destroy+0x80/0x104
 qdisc_create+0x240/0x470
 tc_modify_qdisc+0x1fc/0x6b0
 rtnetlink_rcv_msg+0x12c/0x390
 netlink_rcv_skb+0x5c/0x130
 rtnetlink_rcv+0x1c/0x2c

Fix this by keeping track of the operations we made, and undo the
offload only if we actually did it.

I've added "bool offloaded" inside a 4 byte hole between "int clockid"
and "atomic64_t picos_per_byte". Now the first cache line looks like
below:

$ pahole -C taprio_sched net/sched/sch_taprio.o
struct taprio_sched {
        struct Qdisc * *           qdiscs;               /*     0     8 */
        struct Qdisc *             root;                 /*     8     8 */
        u32                        flags;                /*    16     4 */
        enum tk_offsets            tk_offset;            /*    20     4 */
        int                        clockid;              /*    24     4 */
        bool                       offloaded;            /*    28     1 */

        /* XXX 3 bytes hole, try to pack */

        atomic64_t                 picos_per_byte;       /*    32     0 */

        /* XXX 8 bytes hole, try to pack */

        spinlock_t                 current_entry_lock;   /*    40     0 */

        /* XXX 8 bytes hole, try to pack */

        struct sched_entry *       current_entry;        /*    48     8 */
        struct sched_gate_list *   oper_sched;           /*    56     8 */
        /* --- cacheline 1 boundary (64 bytes) --- */

Fixes: 9c66d15646 ("taprio: Add support for hardware offloading")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
History 2022-09-20 11:41:14 -07:00
arch ARM: SoC fixes for 6.0 2022-09-05 17:44:48 -04:00
block block-6.0-2022-08-26 2022-08-26 11:05:54 -07:00
certs Kbuild updates for v5.20 2022-08-10 10:40:41 -07:00
crypto crypto: blake2b: effectively disable frame size warning 2022-08-10 17:59:11 -07:00
Documentation Documentation: mptcp: fix pm_type formatting 2022-09-13 10:18:44 +02:00
drivers net: enetc: deny offload of tc-based TSN features on VF interfaces 2022-09-20 11:27:10 -07:00
fs Networking fixes for 6.0-rc5, including fixes from rxrpc, netfilter, 2022-09-08 08:15:01 -04:00
include bluetooth pull request for net: 2022-09-19 18:01:04 -07:00
init arm64 fixes for -rc3 2022-08-26 11:32:53 -07:00
io_uring io_uring-6.0-2022-09-02 2022-09-02 16:37:01 -07:00
ipc Updates to various subsystems which I help look after. lib, ocfs2, 2022-08-07 10:03:24 -07:00
kernel Networking fixes for 6.0-rc4, including fixes from bluetooth, bpf 2022-09-01 09:20:42 -07:00
lib This push fixes a boot performance regression due to an unnecessary 2022-08-31 09:47:06 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: pagewalk: Fix race between unmap and page walker 2022-09-03 10:13:13 -07:00
net net/sched: taprio: avoid disabling offload when it was never enabled 2022-09-20 11:41:14 -07:00
samples Tracing updates for 5.20 / 6.0 2022-08-05 09:41:12 -07:00
scripts Makefile.extrawarn: re-enable -Wformat for clang; take 2 2022-09-04 11:15:50 -07:00
security Landlock fix for v6.0-rc4 2022-09-02 15:24:08 -07:00
sound ALSA: usb-audio: Add quirk for LH Labs Geek Out HD Audio 1V5 2022-08-28 09:42:14 +02:00
tools wireguard: selftests: do not install headers on UML 2022-09-20 11:26:14 -07:00
usr Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
virt KVM: Drop unnecessary initialization of "ops" in kvm_ioctl_create_device() 2022-08-19 04:05:43 -04:00
.clang-format PCI/DOE: Add DOE mailbox support functions 2022-07-19 15:38:04 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: split the second line of *.mod into *.usyms 2022-05-08 03:16:59 +09:00
.mailmap .mailmap: update Luca Ceresoli's e-mail address 2022-08-28 14:02:46 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS drm for 5.20/6.0 2022-08-03 19:52:08 -07:00
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 MAINTAINERS: gve: update developers 2022-09-19 15:01:47 -07:00
Makefile Linux 6.0-rc4 2022-09-04 13:10:01 -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.