linux

mainlining shenanigans

Go to file

Christophe Leroy 5eedf9fe8d powerpc/mm: Fix KUAP warning by providing copy_from_kernel_nofault_allowed() Since commit `c331652534` ("powerpc: use non-set_fs based maccess routines"), userspace access is not granted anymore when using copy_from_kernel_nofault() However, kthread_probe_data() uses copy_from_kernel_nofault() to check validity of pointers. When the pointer is NULL, it points to userspace, leading to a KUAP fault and triggering the following big hammer warning many times when you request a sysrq "show task": [ 1117.202054] ------------[ cut here ]------------ [ 1117.202102] Bug: fault blocked by AP register ! [ 1117.202261] WARNING: CPU: 0 PID: 377 at arch/powerpc/include/asm/nohash/32/kup-8xx.h:66 do_page_fault+0x4a8/0x5ec [ 1117.202310] Modules linked in: [ 1117.202428] CPU: 0 PID: 377 Comm: sh Tainted: G W 5.10.0-rc5-01340-g83f53be2de31-dirty #4175 [ 1117.202499] NIP: c0012048 LR: c0012048 CTR: 00000000 [ 1117.202573] REGS: cacdbb88 TRAP: 0700 Tainted: G W (5.10.0-rc5-01340-g83f53be2de31-dirty) [ 1117.202625] MSR: 00021032 <ME,IR,DR,RI> CR: 24082222 XER: 20000000 [ 1117.202899] [ 1117.202899] GPR00: c0012048 cacdbc40 c2929290 00000023 c092e554 00000001 c09865e8 c092e640 [ 1117.202899] GPR08: 00001032 00000000 00000000 00014efc 28082224 100d166a 100a0920 00000000 [ 1117.202899] GPR16: 100cac0c 100b0000 1080c3fc 1080d685 100d0000 100d0000 00000000 100a0900 [ 1117.202899] GPR24: 100d0000 c07892ec 00000000 c0921510 c21f4440 0000005c c0000000 cacdbc80 [ 1117.204362] NIP [c0012048] do_page_fault+0x4a8/0x5ec [ 1117.204461] LR [c0012048] do_page_fault+0x4a8/0x5ec [ 1117.204509] Call Trace: [ 1117.204609] [cacdbc40] [c0012048] do_page_fault+0x4a8/0x5ec (unreliable) [ 1117.204771] [cacdbc70] [c00112f0] handle_page_fault+0x8/0x34 [ 1117.204911] --- interrupt: 301 at copy_from_kernel_nofault+0x70/0x1c0 [ 1117.204979] NIP: c010dbec LR: c010dbac CTR: 00000001 [ 1117.205053] REGS: cacdbc80 TRAP: 0301 Tainted: G W (5.10.0-rc5-01340-g83f53be2de31-dirty) [ 1117.205104] MSR: 00009032 <EE,ME,IR,DR,RI> CR: 28082224 XER: 00000000 [ 1117.205416] DAR: 0000005c DSISR: c0000000 [ 1117.205416] GPR00: c0045948 cacdbd38 c2929290 00000001 00000017 00000017 00000027 0000000f [ 1117.205416] GPR08: c09926ec 00000000 00000000 3ffff000 24082224 [ 1117.206106] NIP [c010dbec] copy_from_kernel_nofault+0x70/0x1c0 [ 1117.206202] LR [c010dbac] copy_from_kernel_nofault+0x30/0x1c0 [ 1117.206258] --- interrupt: 301 [ 1117.206372] [cacdbd38] [c004bbb0] kthread_probe_data+0x44/0x70 (unreliable) [ 1117.206561] [cacdbd58] [c0045948] print_worker_info+0xe0/0x194 [ 1117.206717] [cacdbdb8] [c00548ac] sched_show_task+0x134/0x168 [ 1117.206851] [cacdbdd8] [c005a268] show_state_filter+0x70/0x100 [ 1117.206989] [cacdbe08] [c039baa0] sysrq_handle_showstate+0x14/0x24 [ 1117.207122] [cacdbe18] [c039bf18] __handle_sysrq+0xac/0x1d0 [ 1117.207257] [cacdbe48] [c039c0c0] write_sysrq_trigger+0x4c/0x74 [ 1117.207407] [cacdbe68] [c01fba48] proc_reg_write+0xb4/0x114 [ 1117.207550] [cacdbe88] [c0179968] vfs_write+0x12c/0x478 [ 1117.207686] [cacdbf08] [c0179e60] ksys_write+0x78/0x128 [ 1117.207826] [cacdbf38] [c00110d0] ret_from_syscall+0x0/0x34 [ 1117.207938] --- interrupt: c01 at 0xfd4e784 [ 1117.208008] NIP: 0fd4e784 LR: 0fe0f244 CTR: 10048d38 [ 1117.208083] REGS: cacdbf48 TRAP: 0c01 Tainted: G W (5.10.0-rc5-01340-g83f53be2de31-dirty) [ 1117.208134] MSR: 0000d032 <EE,PR,ME,IR,DR,RI> CR: 44002222 XER: 00000000 [ 1117.208470] [ 1117.208470] GPR00: 00000004 7fc34090 77bfb4e0 00000001 1080fa40 00000002 7400000f fefefeff [ 1117.208470] GPR08: 7f7f7f7f 10048d38 1080c414 7fc343c0 00000000 [ 1117.209104] NIP [0fd4e784] 0xfd4e784 [ 1117.209180] LR [0fe0f244] 0xfe0f244 [ 1117.209236] --- interrupt: c01 [ 1117.209274] Instruction dump: [ 1117.209353] 714a4000 418200f0 73ca0001 40820084 73ca0032 408200f8 73c90040 4082ff60 [ 1117.209727] 0fe00000 3c60c082 386399f4 48013b65 <0fe00000> 80010034 3860000b 7c0803a6 [ 1117.210102] ---[ end trace 1927c0323393af3e ]--- To avoid that, copy_from_kernel_nofault_allowed() is used to check whether the address is a valid kernel address. But the default version of it returns true for any address. Provide a powerpc version of copy_from_kernel_nofault_allowed() that returns false when the address is below TASK_USER_MAX, so that copy_from_kernel_nofault() will return -ERANGE. Fixes: `c331652534` ("powerpc: use non-set_fs based maccess routines") Reported-by: Qian Cai <qcai@redhat.com> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/18bcb456d32a3e74f5ae241fd6f1580c092d07f5.1607360230.git.christophe.leroy@csgroup.eu		2020-12-08 10:22:09 +11:00
arch	powerpc/mm: Fix KUAP warning by providing copy_from_kernel_nofault_allowed()	2020-12-08 10:22:09 +11:00
block	blk-mq: mark flush request as IDLE in flush_end_io()	2020-10-30 08:33:49 -06:00
certs	.gitignore: add SPDX License Identifier	2020-03-25 11:50:48 +01:00
crypto	drivers-5.10-2020-10-12	2020-10-13 13:04:41 -07:00
Documentation	powerpc/64s: flush L1D after user accesses	2020-11-19 23:47:18 +11:00
drivers	Char/Misc fixes/removals for 5.10-rc2	2020-11-01 10:05:16 -08:00
fs	Driver core / Documentation fixes for 5.10-rc2	2020-11-01 09:59:13 -08:00
include	A few fixes for timers/timekeeping:	2020-11-01 11:13:45 -08:00
init	linux-kselftest-kunit-5.10-rc1	2020-10-18 14:45:59 -07:00
ipc	ipc: adjust proc_ipc_sem_dointvec definition to match prototype	2020-09-05 12:14:29 -07:00
kernel	kernel/cpu: add arch override for clear_tasks_mm_cpumask() mm handling	2020-11-27 00:10:39 +11:00
lib	Driver core / Documentation fixes for 5.10-rc2	2020-11-01 09:59:13 -08:00
LICENSES	LICENSES/deprecated: add Zlib license text	2020-09-16 14:33:49 +02:00
mm	mm/process_vm_access: Add missing #include <linux/compat.h>	2020-10-27 12:41:29 -07:00
net	flexible-array member conversion patches for 5.10-rc2	2020-10-31 14:31:28 -07:00
samples	misc: mic: remove the MIC drivers	2020-10-28 19:12:03 +01:00
scripts	scripts: get_abi.pl: assume ReST format by default	2020-10-30 13:16:03 +01:00
security	ima: Replace zero-length array with flexible-array member	2020-10-29 17:22:59 -05:00
sound	ARM: SoC platform updates	2020-10-24 10:33:08 -07:00
tools	selftests/powerpc: refactor entry and rfi_flush tests	2020-11-19 23:47:23 +11:00
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: x86/mmu: Support dirty logging for the TDP MMU	2020-10-23 03:42:13 -04:00
.clang-format	RDMA 5.10 pull request	2020-10-17 11:18:18 -07:00
.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	.gitignore: docs: ignore sphinx_*/ directories	2020-09-10 10:44:31 -06:00
.mailmap	MAINTAINERS: jarkko.sakkinen@linux.intel.com -> jarkko@kernel.org	2020-10-16 11:11:19 -07:00
COPYING	COPYING: state that all contributions really are covered by this file	2020-02-10 13:32:20 -08:00
CREDITS	MAINTAINERS: Move Sangbeom Kim to credits	2020-10-26 10:11:18 +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	Char/Misc fixes/removals for 5.10-rc2	2020-11-01 10:05:16 -08:00
Makefile	Linux 5.10-rc2	2020-11-01 14:43:51 -08:00
README	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -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 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.