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Filename Latest commit message Latest commit date
Ilya Leoshkevich 1fe038030c 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>
2021-08-26 08:36:17 -04:00
arch ARM: dts: nomadik: Fix up interrupt controller node names 2021-08-26 08:36:14 -04:00
block blk-iolatency: error out if blk_get_queue() failed in iolatency_set_limit() 2021-08-12 13:20:58 +02:00
certs
crypto
Documentation KVM: X86: MMU: Use the correct inherited permissions to get shadow page 2021-08-15 13:08:04 +02:00
drivers vhost: Fix the calculation in vhost_overflow() 2021-08-26 08:36:16 -04:00
fs ext4: fix EXT4_MAX_LOGICAL_BLOCK macro 2021-08-26 08:36:11 -04:00
include virtio: Protect vqs list access 2021-08-26 08:36:16 -04:00
init
ipc
kernel bpf: Clear zext_dst of dead insns 2021-08-26 08:36:17 -04:00
lib lib/decompress_unlz4.c: correctly handle zero-padding around initrds. 2021-07-20 16:10:46 +02:00
LICENSES
mm mm: slab: fix kmem_cache_create failed when sysfs node not destroyed 2021-07-25 14:35:14 +02:00
net dccp: add do-while-0 stubs for dccp_pr_debug macros 2021-08-26 08:36:16 -04:00
samples
scripts scripts/tracing: fix the bug that can't parse raw_trace_func 2021-08-12 13:21:00 +02:00
security
sound ASoC: cs42l42: Fix LRCLK frame start edge 2021-08-18 08:56:58 +02:00
tools bpf, selftests: Adjust few selftest result_unpriv outcomes 2021-08-12 13:21:04 +02:00
usr
virt KVM: Do not leak memory for duplicate debugfs directories 2021-08-12 13:21:03 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.142 2021-08-18 08:57:05 +02:00
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.