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Kuniyuki Iwashima a7d6027790 arp: Prevent overflow in arp_req_get().
syzkaller reported an overflown write in arp_req_get(). [0]

When ioctl(SIOCGARP) is issued, arp_req_get() looks up an neighbour
entry and copies neigh->ha to struct arpreq.arp_ha.sa_data.

The arp_ha here is struct sockaddr, not struct sockaddr_storage, so
the sa_data buffer is just 14 bytes.

In the splat below, 2 bytes are overflown to the next int field,
arp_flags.  We initialise the field just after the memcpy(), so it's
not a problem.

However, when dev->addr_len is greater than 22 (e.g. MAX_ADDR_LEN),
arp_netmask is overwritten, which could be set as htonl(0xFFFFFFFFUL)
in arp_ioctl() before calling arp_req_get().

To avoid the overflow, let's limit the max length of memcpy().

Note that commit b5f0de6df6 ("net: dev: Convert sa_data to flexible
array in struct sockaddr") just silenced syzkaller.

[0]:
memcpy: detected field-spanning write (size 16) of single field "r->arp_ha.sa_data" at net/ipv4/arp.c:1128 (size 14)
WARNING: CPU: 0 PID: 144638 at net/ipv4/arp.c:1128 arp_req_get+0x411/0x4a0 net/ipv4/arp.c:1128
Modules linked in:
CPU: 0 PID: 144638 Comm: syz-executor.4 Not tainted 6.1.74 #31
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-5 04/01/2014
RIP: 0010:arp_req_get+0x411/0x4a0 net/ipv4/arp.c:1128
Code: fd ff ff e8 41 42 de fb b9 0e 00 00 00 4c 89 fe 48 c7 c2 20 6d ab 87 48 c7 c7 80 6d ab 87 c6 05 25 af 72 04 01 e8 5f 8d ad fb <0f> 0b e9 6c fd ff ff e8 13 42 de fb be 03 00 00 00 4c 89 e7 e8 a6
RSP: 0018:ffffc900050b7998 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff88803a815000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8641a44a RDI: 0000000000000001
RBP: ffffc900050b7a98 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 203a7970636d656d R12: ffff888039c54000
R13: 1ffff92000a16f37 R14: ffff88803a815084 R15: 0000000000000010
FS:  00007f172bf306c0(0000) GS:ffff88805aa00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f172b3569f0 CR3: 0000000057f12005 CR4: 0000000000770ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
 <TASK>
 arp_ioctl+0x33f/0x4b0 net/ipv4/arp.c:1261
 inet_ioctl+0x314/0x3a0 net/ipv4/af_inet.c:981
 sock_do_ioctl+0xdf/0x260 net/socket.c:1204
 sock_ioctl+0x3ef/0x650 net/socket.c:1321
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __x64_sys_ioctl+0x18e/0x220 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x37/0x90 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x64/0xce
RIP: 0033:0x7f172b262b8d
Code: 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f172bf300b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f172b3abf80 RCX: 00007f172b262b8d
RDX: 0000000020000000 RSI: 0000000000008954 RDI: 0000000000000003
RBP: 00007f172b2d3493 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f172b3abf80 R15: 00007f172bf10000
 </TASK>

Reported-by: syzkaller <syzkaller@googlegroups.com>
Reported-by: Bjoern Doebel <doebel@amazon.de>
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240215230516.31330-1-kuniyu@amazon.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2024-02-20 10:50:19 +01:00
arch xen: branch for v6.8-rc5 2024-02-15 11:33:35 -08:00
block blk-iocost: Fix an UBSAN shift-out-of-bounds warning 2024-02-08 10:11:39 -07:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto crypto: algif_hash - Remove bogus SGL free on zero-length error path 2024-02-02 18:08:12 +08:00
Documentation Including fixes from can, wireless and netfilter. 2024-02-15 11:39:27 -08:00
drivers enic: Avoid false positive under FORTIFY_SOURCE 2024-02-19 10:57:27 +00:00
fs for-6.8-rc4-tag 2024-02-14 15:47:02 -08:00
include mptcp: fix lockless access in subflow ULP diag 2024-02-18 10:25:00 +00:00
init update workarounds for gcc "asm goto" issue 2024-02-15 11:14:33 -08:00
io_uring io_uring/net: fix sr->len for IORING_OP_RECV with MSG_WAITALL and buffers 2024-02-01 06:42:36 -07:00
ipc shm: Slim down dependencies 2023-12-20 19:26:31 -05:00
kernel - Make sure a warning is issued when a hrtimer gets queued after the 2024-02-11 11:44:14 -08:00
lib linux_kselftest-kunit-fixes-6.8-rc5 2024-02-14 15:34:03 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/memory: Use exception ip to search exception tables 2024-02-12 23:04:42 +01:00
net arp: Prevent overflow in arp_req_get(). 2024-02-20 10:50:19 +01:00
rust Rust changes for v6.8 2024-01-11 13:05:41 -08:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-09 15:57:48 -08:00
scripts Kbuild fixes for v6.8 2024-02-01 11:57:42 -08:00
security lsm/stable-6.8 PR 20240131 2024-02-01 10:00:28 -08:00
sound ASoC: Fixes for v6.8 2024-02-01 19:40:42 +01:00
tools selftests: bonding: set active slave to primary eth1 specifically 2024-02-19 09:11:35 +00:00
usr Kbuild updates for v6.8 2024-01-18 17:57:07 -08:00
virt Generic: 2024-01-17 13:03:37 -08:00
.clang-format clang-format: Update with v6.7-rc4's for_each macro list 2023-12-08 23:54:38 +01:00
.cocciconfig
.editorconfig Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.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 Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.mailmap Including fixes from can, wireless and netfilter. 2024-02-15 11:39:27 -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: supplement of zswap maintainers update 2024-01-25 23:52:21 -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 Including fixes from can, wireless and netfilter. 2024-02-15 11:39:27 -08:00
Makefile Linux 6.8-rc4 2024-02-11 12:18:13 -08:00
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.