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Christophe Leroy dc9c5166c3 powerpc/code-patching: Disable KASAN report during patching via temporary mm
Erhard reports the following KASAN hit on Talos II (power9) with kernel 6.13:

[   12.028126] ==================================================================
[   12.028198] BUG: KASAN: user-memory-access in copy_to_kernel_nofault+0x8c/0x1a0
[   12.028260] Write of size 8 at addr 0000187e458f2000 by task systemd/1

[   12.028346] CPU: 87 UID: 0 PID: 1 Comm: systemd Tainted: G                T  6.13.0-P9-dirty #3
[   12.028408] Tainted: [T]=RANDSTRUCT
[   12.028446] Hardware name: T2P9D01 REV 1.01 POWER9 0x4e1202 opal:skiboot-bc106a0 PowerNV
[   12.028500] Call Trace:
[   12.028536] [c000000008dbf3b0] [c000000001656a48] dump_stack_lvl+0xbc/0x110 (unreliable)
[   12.028609] [c000000008dbf3f0] [c0000000006e2fc8] print_report+0x6b0/0x708
[   12.028666] [c000000008dbf4e0] [c0000000006e2454] kasan_report+0x164/0x300
[   12.028725] [c000000008dbf600] [c0000000006e54d4] kasan_check_range+0x314/0x370
[   12.028784] [c000000008dbf640] [c0000000006e6310] __kasan_check_write+0x20/0x40
[   12.028842] [c000000008dbf660] [c000000000578e8c] copy_to_kernel_nofault+0x8c/0x1a0
[   12.028902] [c000000008dbf6a0] [c0000000000acfe4] __patch_instructions+0x194/0x210
[   12.028965] [c000000008dbf6e0] [c0000000000ade80] patch_instructions+0x150/0x590
[   12.029026] [c000000008dbf7c0] [c0000000001159bc] bpf_arch_text_copy+0x6c/0xe0
[   12.029085] [c000000008dbf800] [c000000000424250] bpf_jit_binary_pack_finalize+0x40/0xc0
[   12.029147] [c000000008dbf830] [c000000000115dec] bpf_int_jit_compile+0x3bc/0x930
[   12.029206] [c000000008dbf990] [c000000000423720] bpf_prog_select_runtime+0x1f0/0x280
[   12.029266] [c000000008dbfa00] [c000000000434b18] bpf_prog_load+0xbb8/0x1370
[   12.029324] [c000000008dbfb70] [c000000000436ebc] __sys_bpf+0x5ac/0x2e00
[   12.029379] [c000000008dbfd00] [c00000000043a228] sys_bpf+0x28/0x40
[   12.029435] [c000000008dbfd20] [c000000000038eb4] system_call_exception+0x334/0x610
[   12.029497] [c000000008dbfe50] [c00000000000c270] system_call_vectored_common+0xf0/0x280
[   12.029561] --- interrupt: 3000 at 0x3fff82f5cfa8
[   12.029608] NIP:  00003fff82f5cfa8 LR: 00003fff82f5cfa8 CTR: 0000000000000000
[   12.029660] REGS: c000000008dbfe80 TRAP: 3000   Tainted: G                T   (6.13.0-P9-dirty)
[   12.029735] MSR:  900000000280f032 <SF,HV,VEC,VSX,EE,PR,FP,ME,IR,DR,RI>  CR: 42004848  XER: 00000000
[   12.029855] IRQMASK: 0
               GPR00: 0000000000000169 00003fffdcf789a0 00003fff83067100 0000000000000005
               GPR04: 00003fffdcf78a98 0000000000000090 0000000000000000 0000000000000008
               GPR08: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
               GPR12: 0000000000000000 00003fff836ff7e0 c000000000010678 0000000000000000
               GPR16: 0000000000000000 0000000000000000 00003fffdcf78f28 00003fffdcf78f90
               GPR20: 0000000000000000 0000000000000000 0000000000000000 00003fffdcf78f80
               GPR24: 00003fffdcf78f70 00003fffdcf78d10 00003fff835c7239 00003fffdcf78bd8
               GPR28: 00003fffdcf78a98 0000000000000000 0000000000000000 000000011f547580
[   12.030316] NIP [00003fff82f5cfa8] 0x3fff82f5cfa8
[   12.030361] LR [00003fff82f5cfa8] 0x3fff82f5cfa8
[   12.030405] --- interrupt: 3000
[   12.030444] ==================================================================

Commit c28c15b6d2 ("powerpc/code-patching: Use temporary mm for
Radix MMU") is inspired from x86 but unlike x86 is doesn't disable
KASAN reports during patching. This wasn't a problem at the begining
because __patch_mem() is not instrumented.

Commit 465cabc97b ("powerpc/code-patching: introduce
patch_instructions()") use copy_to_kernel_nofault() to copy several
instructions at once. But when using temporary mm the destination is
not regular kernel memory but a kind of kernel-like memory located
in user address space. Because it is not in kernel address space it is
not covered by KASAN shadow memory. Since commit e4137f0881 ("mm,
kasan, kmsan: instrument copy_from/to_kernel_nofault") KASAN reports
bad accesses from copy_to_kernel_nofault(). Here a bad access to user
memory is reported because KASAN detects the lack of shadow memory and
the address is below TASK_SIZE.

Do like x86 in commit b3fd8e83ad ("x86/alternatives: Use temporary
mm for text poking") and disable KASAN reports during patching when
using temporary mm.

Reported-by: Erhard Furtner <erhard_f@mailbox.org>
Close: https://lore.kernel.org/all/20250201151435.48400261@yea/
Fixes: 465cabc97b ("powerpc/code-patching: introduce patch_instructions()")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/1c05b2a1b02ad75b981cfc45927e0b4a90441046.1738577687.git.christophe.leroy@csgroup.eu
2025-02-10 09:56:02 +05:30
arch powerpc/code-patching: Disable KASAN report during patching via temporary mm 2025-02-10 09:56:02 +05:30
block block-6.14-20250131 2025-01-31 11:49:30 -08:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
Documentation ARM: 2025-02-09 09:41:38 -08:00
drivers Additional power management fix for 6.14-rc2 2025-02-09 09:47:06 -08:00
fs four SMB3 client fixes, 3 DFS related 2025-02-07 19:23:06 -08:00
include Kbuild fixes for v6.14 2025-02-09 10:05:32 -08:00
init Kbuild updates for v6.14 2025-01-31 12:07:07 -08:00
io_uring Fix a dangling pointer bug in the futex code used by the 2025-02-08 10:54:11 -08:00
ipc treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
kernel seccomp fix for v6.14-rc2 2025-02-08 14:04:21 -08:00
lib hardening fixes for v6.14-rc2 2025-02-08 14:12:17 -08:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm assorted stuff for this merge window 2025-02-01 15:07:56 -08:00
net vfs-6.14-rc2.fixes 2025-02-07 09:22:31 -08:00
rust rust: kbuild: do not export generated KASAN ODR symbols 2025-02-06 19:47:04 +01:00
samples AT_EXECVE_CHECK update for v6.14-rc1 (fix1) 2025-01-31 17:12:31 -08:00
scripts Kbuild fixes for v6.14 2025-02-09 10:05:32 -08:00
security treewide: const qualify ctl_tables where applicable 2025-01-28 13:48:37 +01:00
sound sound fixes for 6.14-rc1 2025-01-31 09:17:02 -08:00
tools ARM: 2025-02-09 09:41:38 -08:00
usr kbuild: Drop support for include/asm-<arch> in headers_check.pl 2024-12-21 11:43:17 +09:00
virt KVM: remove kvm_arch_post_init_vm 2025-02-04 11:27:45 -05:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.clippy.toml rust: give Clippy the minimum supported Rust version 2025-01-10 00:17:25 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: Retire Ralf Baechle 2024-11-12 15:48:59 +01:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: use host dylib naming convention to support macOS 2025-01-10 01:01:24 +01:00
.mailmap 21 hotfixes. 8 are cc:stable and the remainder address post-6.13 issues. 2025-02-01 09:49:20 -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: Move Pavel to kernel.org address 2025-02-07 09:12:33 -08:00
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 gpio fixes for v6.14-rc2 2025-02-07 09:50:33 -08:00
Makefile Linux 6.14-rc2 2025-02-09 12:45:03 -08:00
README README: Fix spelling 2024-03-18 03:36:32 -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 reStructuredText 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.