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Andrii Nakryiko 0a40c609e2 bpf: Ensure proper register state printing for cond jumps
[ Upstream commit 1a8a315f008a58f54fecb012b928aa6a494435b3 ]

Verifier emits relevant register state involved in any given instruction
next to it after `;` to the right, if possible. Or, worst case, on the
separate line repeating instruction index.

E.g., a nice and simple case would be:

  2: (d5) if r0 s<= 0x0 goto pc+1       ; R0_w=0

But if there is some intervening extra output (e.g., precision
backtracking log) involved, we are supposed to see the state after the
precision backtrack log:

  4: (75) if r0 s>= 0x0 goto pc+1
  mark_precise: frame0: last_idx 4 first_idx 0 subseq_idx -1
  mark_precise: frame0: regs=r0 stack= before 2: (d5) if r0 s<= 0x0 goto pc+1
  mark_precise: frame0: regs=r0 stack= before 1: (b7) r0 = 0
  6: R0_w=0

First off, note that in `6: R0_w=0` instruction index corresponds to the
next instruction, not to the conditional jump instruction itself, which
is wrong and we'll get to that.

But besides that, the above is a happy case that does work today. Yet,
if it so happens that precision backtracking had to traverse some of the
parent states, this `6: R0_w=0` state output would be missing.

This is due to a quirk of print_verifier_state() routine, which performs
mark_verifier_state_clean(env) at the end. This marks all registers as
"non-scratched", which means that subsequent logic to print *relevant*
registers (that is, "scratched ones") fails and doesn't see anything
relevant to print and skips the output altogether.

print_verifier_state() is used both to print instruction context, but
also to print an **entire** verifier state indiscriminately, e.g.,
during precision backtracking (and in a few other situations, like
during entering or exiting subprogram).  Which means if we have to print
entire parent state before getting to printing instruction context
state, instruction context is marked as clean and is omitted.

Long story short, this is definitely not intentional. So we fix this
behavior in this patch by teaching print_verifier_state() to clear
scratch state only if it was used to print instruction state, not the
parent/callback state. This is determined by print_all option, so if
it's not set, we don't clear scratch state. This fixes missing
instruction state for these cases.

As for the mismatched instruction index, we fix that by making sure we
call print_insn_state() early inside check_cond_jmp_op() before we
adjusted insn_idx based on jump branch taken logic. And with that we get
desired correct information:

  9: (16) if w4 == 0x1 goto pc+9
  mark_precise: frame0: last_idx 9 first_idx 9 subseq_idx -1
  mark_precise: frame0: parent state regs=r4 stack=: R2_w=1944 R4_rw=P1 R10=fp0
  mark_precise: frame0: last_idx 8 first_idx 0 subseq_idx 9
  mark_precise: frame0: regs=r4 stack= before 8: (66) if w4 s> 0x3 goto pc+5
  mark_precise: frame0: regs=r4 stack= before 7: (b7) r4 = 1
  9: R4=1

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20231011223728.3188086-6-andrii@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-11-28 17:06:56 +00:00
arch x86/mm: Drop the 4 MB restriction on minimal NUMA node memory size 2023-11-28 17:06:55 +00:00
block blk-core: use pr_warn_ratelimited() in bio_check_ro() 2023-11-20 11:52:17 +01:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: lrw,xts - Replace strlcpy with strscpy 2023-09-23 11:11:01 +02:00
Documentation smp,csd: Throw an error if a CSD lock is stuck for too long 2023-11-28 17:06:55 +00:00
drivers wifi: ath10k: Don't touch the CE interrupt registers after power up 2023-11-28 17:06:56 +00:00
fs btrfs: use u64 for buffer sizes in the tree search ioctls 2023-11-20 11:52:18 +01:00
include vsock: read from socket's error queue 2023-11-28 17:06:56 +00:00
init sched/psi: Select KERNFS as needed 2023-09-13 09:42:28 +02:00
io_uring io_uring/net: ensure socket is marked connected on connect retry 2023-11-20 11:52:18 +01:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel bpf: Ensure proper register state printing for cond jumps 2023-11-28 17:06:56 +00:00
lib lib/generic-radix-tree.c: Don't overflow in peek() 2023-11-28 17:06:54 +00:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm filemap: add filemap_get_folios_tag() 2023-11-20 11:52:09 +01:00
net vsock: read from socket's error queue 2023-11-28 17:06:56 +00:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples fprobe: Pass entry_data to handlers 2023-10-25 12:03:12 +02:00
scripts modpost: fix ishtp MODULE_DEVICE_TABLE built on big-endian host 2023-11-20 11:52:12 +01:00
security apparmor: fix invalid reference on profile->disconnected 2023-11-20 11:52:09 +01:00
sound ASoC: dapm: fix clock get name 2023-11-20 11:52:18 +01:00
tools selftests/lkdtm: Disable CONFIG_UBSAN_TRAP in test config 2023-11-28 17:06:54 +00:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add() 2023-09-13 09:42:46 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig
.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: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.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 MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
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 devlink: move code to a dedicated directory 2023-08-30 16:11:00 +02:00
Makefile Linux 6.1.63 2023-11-20 11:52:19 +01:00
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.