github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-06-06 05:27:07 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph
Linux kernel source tree
982,857 Commits 1 Branch 933 Tags 20 GiB
C 97%
Assembly 1%
Shell 0.6%
Rust 0.5%
Python 0.4%
Other 0.3%
ad97425d23
Go to file
Alexandru Elisei ad97425d23 arm64: compat: Do not treat syscall number as ESR_ELx for a bad syscall 
[ Upstream commit 3fed9e5514 ]

If a compat process tries to execute an unknown system call above the
__ARM_NR_COMPAT_END number, the kernel sends a SIGILL signal to the
offending process. Information about the error is printed to dmesg in
compat_arm_syscall() -> arm64_notify_die() -> arm64_force_sig_fault() ->
arm64_show_signal().

arm64_show_signal() interprets a non-zero value for
current->thread.fault_code as an exception syndrome and displays the
message associated with the ESR_ELx.EC field (bits 31:26).
current->thread.fault_code is set in compat_arm_syscall() ->
arm64_notify_die() with the bad syscall number instead of a valid ESR_ELx
value. This means that the ESR_ELx.EC field has the value that the user set
for the syscall number and the kernel can end up printing bogus exception
messages*. For example, for the syscall number 0x68000000, which evaluates
to ESR_ELx.EC value of 0x1A (ESR_ELx_EC_FPAC) the kernel prints this error:

[   18.349161] syscall[300]: unhandled exception: ERET/ERETAA/ERETAB, ESR 0x68000000, Oops - bad compat syscall(2) in syscall[10000+50000]
[   18.350639] CPU: 2 PID: 300 Comm: syscall Not tainted 5.18.0-rc1 #79
[   18.351249] Hardware name: Pine64 RockPro64 v2.0 (DT)
[..]

which is misleading, as the bad compat syscall has nothing to do with
pointer authentication.

Stop arm64_show_signal() from printing exception syndrome information by
having compat_arm_syscall() set the ESR_ELx value to 0, as it has no
meaning for an invalid system call number. The example above now becomes:

[   19.935275] syscall[301]: unhandled exception: Oops - bad compat syscall(2) in syscall[10000+50000]
[   19.936124] CPU: 1 PID: 301 Comm: syscall Not tainted 5.18.0-rc1-00005-g7e08006d4102 #80
[   19.936894] Hardware name: Pine64 RockPro64 v2.0 (DT)
[..]

which although shows less information because the syscall number,
wrongfully advertised as the ESR value, is missing, it is better than
showing plainly wrong information. The syscall number can be easily
obtained with strace.

*A 32-bit value above or equal to 0x8000_0000 is interpreted as a negative
integer in compat_arm_syscal() and the condition scno < __ARM_NR_COMPAT_END
evaluates to true; the syscall will exit to userspace in this case with the
ENOSYS error code instead of arm64_notify_die() being called.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220425114444.368693-3-alexandru.elisei@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-06-09 10:20:53 +02:00
arch arm64: compat: Do not treat syscall number as ESR_ELx for a bad syscall 2022-06-09 10:20:53 +02:00
block block-map: add __GFP_ZERO flag for alloc_page in function bio_copy_kern 2022-05-12 12:25:45 +02:00
certs certs: Trigger creation of RSA module signing key if it's not an RSA key 2021-09-15 09:50:29 +02:00
crypto crypto: ecrdsa - Fix incorrect use of vli_cmp 2022-06-06 08:42:43 +02:00
Documentation docs: submitting-patches: Fix crossref to 'The canonical patch format' 2022-06-06 08:42:44 +02:00
drivers ath10k: skip ath10k_halt during suspend for driver state RESTARTING 2022-06-09 10:20:53 +02:00
fs btrfs: repair super block num_devices automatically 2022-06-09 10:20:49 +02:00
include ALSA: jack: Access input_dev under mutex 2022-06-09 10:20:51 +02:00
init random: handle latent entropy and command line from random_init() 2022-05-30 09:33:44 +02:00
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-12-01 09:19:10 +01:00
kernel rcu: Make TASKS_RUDE_RCU select IRQ_WORK 2022-06-09 10:20:51 +02:00
lib lib/crypto: add prompts back to crypto libraries 2022-06-06 08:42:42 +02:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm zsmalloc: fix races between asynchronous zspage free and page migration 2022-06-06 08:42:43 +02:00
net ipv6: fix locking issues with loops over idev->addr_list 2022-06-09 10:20:50 +02:00
samples samples/bpf, xdpsock: Fix race when running for fix duration of time 2022-04-08 14:40:21 +02:00
scripts gcc-plugins: latent_entropy: use /dev/urandom 2022-04-20 09:23:26 +02:00
security lockdown: also lock down previous kgdb use 2022-05-30 09:33:22 +02:00
sound ASoC: Intel: bytcr_rt5640: Add quirk for the HP Pro Tablet 408 2022-06-09 10:20:52 +02:00
tools tools/power turbostat: fix ICX DRAM power numbers 2022-06-09 10:20:51 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:25:48 +01:00
virt KVM: Prevent module exit until all VMs are freed 2022-04-08 14:40:38 +02:00
.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 kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +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 MAINTAINERS: add git tree for random.c 2022-05-30 09:33:24 +02:00
Makefile Linux 5.10.120 2022-06-06 08:42:45 +02:00
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.