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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		History 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

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 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.