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Nick Desaulniers ac0dbed9ba net: seg6: initialize induction variable to first valid array index
Fixes the following warnings observed when building
CONFIG_IPV6_SEG6_LWTUNNEL=y with clang:

  net/ipv6/seg6_local.o: warning: objtool: seg6_local_fill_encap() falls
  through to next function seg6_local_get_encap_size()
  net/ipv6/seg6_local.o: warning: objtool: seg6_local_cmp_encap() falls
  through to next function input_action_end()

LLVM can fully unroll loops in seg6_local_get_encap_size() and
seg6_local_cmp_encap(). One issue in those loops is that the induction
variable is initialized to 0. The loop iterates over members of
seg6_action_params, a global array of struct seg6_action_param calling
their put() function pointer members.  seg6_action_param uses an array
initializer to initialize SEG6_LOCAL_SRH and later elements, which is
the third enumeration of an anonymous union.

The guard `if (attrs & SEG6_F_ATTR(i))` may prevent this from being
called at runtime, but it would still be UB for
`seg6_action_params[0]->put` to be called; the unrolled loop will make
the initial iterations unreachable, which LLVM will later rotate to
fallthrough to the next function.

Make this more obvious that this cannot happen to the compiler by
initializing the loop induction variable to the minimum valid index that
seg6_action_params is initialized to.

Reported-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20220802161203.622293-1-ndesaulniers@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-08-05 19:34:54 -07:00
arch Networking changes for 6.0. 2022-08-03 16:29:08 -07:00
block iov_iter work, part 1 - isolated cleanups and optimizations. 2022-08-03 13:50:22 -07:00
certs certs: make system keyring depend on x509 parser 2022-07-24 12:53:55 -07:00
crypto This update includes the following changes: 2022-08-02 17:45:14 -07:00
Documentation docs: net: bonding: remove mentions of trans_start 2022-08-03 19:20:13 -07:00
drivers net: bcmgenet: Indicate MAC is in charge of PHY PM 2022-08-05 19:02:18 -07:00
fs zonefs changes for 5.20-rc1 2022-08-03 15:21:53 -07:00
include net: bonding: replace dev_trans_start() with the jiffies of the last ARP/NS 2022-08-03 19:20:12 -07:00
init Several core optimizations: 2022-08-03 09:45:08 -07:00
io_uring iov_iter work, part 1 - isolated cleanups and optimizations. 2022-08-03 13:50:22 -07:00
ipc ipc: Free mq_sysctls if ipc namespace creation failed 2022-06-22 17:47:41 -05:00
kernel Networking changes for 6.0. 2022-08-03 16:29:08 -07:00
lib Networking changes for 6.0. 2022-08-03 16:29:08 -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 for-5.20-tag 2022-08-03 14:54:52 -07:00
net net: seg6: initialize induction variable to first valid array index 2022-08-05 19:34:54 -07:00
samples Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2022-07-22 16:55:44 -07:00
scripts Networking changes for 6.0. 2022-08-03 16:29:08 -07:00
security linux-kselftest-kunit-5.20-rc1 2022-08-02 19:34:45 -07:00
sound ASoC: Drop Rockchip BCLK management for v5.19 2022-07-15 12:31:07 +02:00
tools selftests: netfilter: add test case for nf trace infrastructure 2022-08-05 18:50:15 -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: x86: disable preemption around the call to kvm_arch_vcpu_{un|}blocking 2022-06-09 10:52:20 -04:00
.clang-format clang-format: Fix space after for_each macros 2022-05-20 19:27:16 +02:00
.cocciconfig
.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 kbuild: split the second line of *.mod into *.usyms 2022-05-08 03:16:59 +09:00
.mailmap ARM: SoC fixes for 5.19, part 4 2022-07-27 09:43:07 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: mark ARM/PALM TREO SUPPORT orphan 2022-07-07 15:17:00 +02:00
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: Update ibmveth maintainer 2022-08-05 18:53:11 -07:00
Makefile linux-kselftest-next-5.20-rc1 2022-08-02 19:44:56 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.