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Kuniyuki Iwashima 302fe8dd14 af_unix: Annotate data-race around unix_sk(sk)->addr.
[ Upstream commit 97e1db06c7 ]

Once unix_sk(sk)->addr is assigned under net->unx.table.locks and
unix_sk(sk)->bindlock, *(unix_sk(sk)->addr) and unix_sk(sk)->path are
fully set up, and unix_sk(sk)->addr is never changed.

unix_getname() and unix_copy_addr() access the two fields locklessly,
and commit ae3b564179 ("missing barriers in some of unix_sock ->addr
and ->path accesses") added smp_store_release() and smp_load_acquire()
pairs.

In other functions, we still read unix_sk(sk)->addr locklessly to check
if the socket is bound, and KCSAN complains about it.  [0]

Given these functions have no dependency for *(unix_sk(sk)->addr) and
unix_sk(sk)->path, READ_ONCE() is enough to annotate the data-race.

Note that it is safe to access unix_sk(sk)->addr locklessly if the socket
is found in the hash table.  For example, the lockless read of otheru->addr
in unix_stream_connect() is safe.

Note also that newu->addr there is of the child socket that is still not
accessible from userspace, and smp_store_release() publishes the address
in case the socket is accept()ed and unix_getname() / unix_copy_addr()
is called.

[0]:
BUG: KCSAN: data-race in unix_bind / unix_listen

write (marked) to 0xffff88805f8d1840 of 8 bytes by task 13723 on cpu 0:
 __unix_set_addr_hash net/unix/af_unix.c:329 [inline]
 unix_bind_bsd net/unix/af_unix.c:1241 [inline]
 unix_bind+0x881/0x1000 net/unix/af_unix.c:1319
 __sys_bind+0x194/0x1e0 net/socket.c:1847
 __do_sys_bind net/socket.c:1858 [inline]
 __se_sys_bind net/socket.c:1856 [inline]
 __x64_sys_bind+0x40/0x50 net/socket.c:1856
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x4f/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x46/0x4e

read to 0xffff88805f8d1840 of 8 bytes by task 13724 on cpu 1:
 unix_listen+0x72/0x180 net/unix/af_unix.c:734
 __sys_listen+0xdc/0x160 net/socket.c:1881
 __do_sys_listen net/socket.c:1890 [inline]
 __se_sys_listen net/socket.c:1888 [inline]
 __x64_sys_listen+0x2e/0x40 net/socket.c:1888
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x4f/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x46/0x4e

value changed: 0x0000000000000000 -> 0xffff88807b5b1b40

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 13724 Comm: syz-executor.4 Not tainted 6.8.0-12822-gcd51db110a7e #12
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Reported-by: syzkaller <syzkaller@googlegroups.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240522154002.77857-1-kuniyu@amazon.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2024-06-12 11:12:55 +02:00
arch arm64: asm-bug: Add .align 2 to the end of __BUG_ENTRY 2024-06-12 11:12:49 +02:00
block blk-cgroup: Properly propagate the iostat update up the hierarchy 2024-06-12 11:12:46 +02:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto KEYS: asymmetric: Add missing dependencies of FIPS_SIGNATURE_SELFTEST 2024-06-12 11:11:22 +02:00
Documentation dt-bindings: adc: axi-adc: add clocks property 2024-06-12 11:12:36 +02:00
drivers enic: Validate length of nl attributes in enic_set_vf_port 2024-06-12 11:12:55 +02:00
fs kthread: add kthread_stop_put 2024-06-12 11:12:52 +02:00
include net/mlx5: Fix MTMP register capability offset in MCAM register 2024-06-12 11:12:54 +02:00
init rust: make mutually exclusive with CFI_CLANG 2024-05-02 16:32:42 +02:00
io_uring io-wq: write next_work before dropping acct_lock 2024-06-12 11:11:33 +02:00
ipc Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
kernel dma-mapping: benchmark: handle NUMA_NO_NODE correctly 2024-06-12 11:12:52 +02:00
lib lib/test_hmm.c: handle src_pfns and dst_pfns allocation failure 2024-06-12 11:12:08 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm kthread: add kthread_stop_put 2024-06-12 11:12:52 +02:00
net af_unix: Annotate data-race around unix_sk(sk)->addr. 2024-06-12 11:12:55 +02:00
rust rust: kernel: require Send for Module implementations 2024-05-17 12:01:56 +02:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-23 09:24:47 +01:00
scripts s390/vdso: Create .build-id links for unstripped vdso files 2024-06-12 11:12:33 +02:00
security KEYS: trusted: Do not use WARN when encode fails 2024-05-25 16:22:55 +02:00
sound ALSA: hda/realtek: Adjust G814JZR to use SPI init for amp 2024-06-12 11:12:55 +02:00
tools bpf: Fix potential integer overflow in resolve_btfids 2024-06-12 11:12:54 +02:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt KVM: Always flush async #PF workqueue when vCPU is being destroyed 2024-04-03 15:28:18 +02:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: rename binkernel.spec to kernel.spec 2023-07-25 00:59:33 +09:00
.mailmap 20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues 2023-10-24 09:52:16 -10:00
.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 USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
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 pwm: Rename pwm_apply_state() to pwm_apply_might_sleep() 2024-06-12 11:12:24 +02:00
Makefile kbuild: unify vdso_install rules 2024-06-12 11:12:32 +02:00
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.