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Ilya Leoshkevich a687a4733b bpf: Clear zext_dst of dead insns
[ Upstream commit 45c709f8c71b525b51988e782febe84ce933e7e0 ]

"access skb fields ok" verifier test fails on s390 with the "verifier
bug. zext_dst is set, but no reg is defined" message. The first insns
of the test prog are ...

   0:	61 01 00 00 00 00 00 00 	ldxw %r0,[%r1+0]
   8:	35 00 00 01 00 00 00 00 	jge %r0,0,1
  10:	61 01 00 08 00 00 00 00 	ldxw %r0,[%r1+8]

... and the 3rd one is dead (this does not look intentional to me, but
this is a separate topic).

sanitize_dead_code() converts dead insns into "ja -1", but keeps
zext_dst. When opt_subreg_zext_lo32_rnd_hi32() tries to parse such
an insn, it sees this discrepancy and bails. This problem can be seen
only with JITs whose bpf_jit_needs_zext() returns true.

Fix by clearning dead insns' zext_dst.

The commits that contributed to this problem are:

1. 5aa5bd14c5 ("bpf: add initial suite for selftests"), which
   introduced the test with the dead code.
2. 5327ed3d44 ("bpf: verifier: mark verified-insn with
   sub-register zext flag"), which introduced the zext_dst flag.
3. 83a2881903f3 ("bpf: Account for BPF_FETCH in
   insn_has_def32()"), which introduced the sanity check.
4. 9183671af6db ("bpf: Fix leakage under speculation on
   mispredicted branches"), which bisect points to.

It's best to fix this on stable branches that contain the second one,
since that's the point where the inconsistency was introduced.

Fixes: 5327ed3d44 ("bpf: verifier: mark verified-insn with sub-register zext flag")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210812151811.184086-2-iii@linux.ibm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-07-05 18:55:46 +02:00
arch arm64: dts: qcom: msm8992-bullhead: Remove PSCI 2024-07-05 18:55:45 +02:00
block blk-iolatency: error out if blk_get_queue() failed in iolatency_set_limit() 2024-07-05 18:52:09 +02:00
certs certs: add 'x509_revocation_list' to gitignore 2021-07-20 16:05:35 +02:00
crypto init: add dsm gpl source 2024-07-05 18:00:04 +02:00
Documentation init: add dsm gpl source 2024-07-05 18:00:04 +02:00
drivers drm/mediatek: Add AAL output size configuration 2024-07-05 18:55:45 +02:00
fs vboxsf: Add support for the atomic_open directory-inode op 2024-07-05 18:54:41 +02:00
include soc / drm: mediatek: Move DDP component defines into mtk-mmsys.h 2024-07-05 18:55:45 +02:00
init init: add dsm gpl source 2024-07-05 18:00:04 +02:00
ipc ipc/mqueue, msg, sem: avoid relying on a stack reference past its expiry 2021-05-26 12:06:54 +02:00
kernel bpf: Clear zext_dst of dead insns 2024-07-05 18:55:46 +02:00
lib init: add dsm gpl source 2024-07-05 18:00:04 +02:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm init: add dsm gpl source 2024-07-05 18:00:04 +02:00
net dccp: add do-while-0 stubs for dccp_pr_debug macros 2024-07-05 18:55:45 +02:00
samples samples/bpf: Fix the error return code of xdp_redirect's main() 2021-07-14 16:56:23 +02:00
scripts scripts/tracing: fix the bug that can't parse raw_trace_func 2024-07-05 18:52:27 +02:00
security bpf: Add lockdown check for probe_write_user helper 2024-07-05 18:53:10 +02:00
sound ASoC: cs42l42: Fix LRCLK frame start edge 2024-07-05 18:54:11 +02:00
SynoBuildConf init: add dsm gpl source 2024-07-05 18:00:04 +02:00
synology init: add dsm gpl source 2024-07-05 18:00:04 +02:00
tools libbpf: Fix probe for BPF_PROG_TYPE_CGROUP_SOCKOPT 2024-07-05 18:54:12 +02:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt KVM: Do not leak memory for duplicate debugfs directories 2024-07-05 18:52:31 +02:00
.clang-format init: add dsm gpl source 2024-07-05 18:00:04 +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: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
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 init: add dsm gpl source 2024-07-05 18:00:04 +02:00
Makefile init: add dsm gpl source 2024-07-05 18:00:04 +02:00
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.