CVE-2024-26862

In the Linux kernel, the following vulnerability has been resolved:

packet: annotate data-races around ignore_outgoing

ignore_outgoing is read locklessly from dev_queue_xmit_nit() and packet_getsockopt()

Add appropriate READ_ONCE()/WRITE_ONCE() annotations.

syzbot reported:

BUG: KCSAN: data-race in dev_queue_xmit_nit / packet_setsockopt

write to 0xffff888107804542 of 1 bytes by task 22618 on cpu 0: packet_setsockopt+0xd83/0xfd0 net/packet/af_packet.c:4003 do_sock_setsockopt net/socket.c:2311 [inline] __sys_setsockopt+0x1d8/0x250 net/socket.c:2334 __do_sys_setsockopt net/socket.c:2343 [inline] __se_sys_setsockopt net/socket.c:2340 [inline] __x64_sys_setsockopt+0x66/0x80 net/socket.c:2340 do_syscall_64+0xd3/0x1d0 entry_SYSCALL_64_after_hwframe+0x6d/0x75

read to 0xffff888107804542 of 1 bytes by task 27 on cpu 1: dev_queue_xmit_nit+0x82/0x620 net/core/dev.c:2248 xmit_one net/core/dev.c:3527 [inline] dev_hard_start_xmit+0xcc/0x3f0 net/core/dev.c:3547 __dev_queue_xmit+0xf24/0x1dd0 net/core/dev.c:4335 dev_queue_xmit include/linux/netdevice.h:3091 [inline] batadv_send_skb_packet+0x264/0x300 net/batman-adv/send.c:108 batadv_send_broadcast_skb+0x24/0x30 net/batman-adv/send.c:127 batadv_iv_ogm_send_to_if net/batman-adv/bat_iv_ogm.c:392 [inline] batadv_iv_ogm_emit net/batman-adv/bat_iv_ogm.c:420 [inline] batadv_iv_send_outstanding_bat_ogm_packet+0x3f0/0x4b0 net/batman-adv/bat_iv_ogm.c:1700 process_one_work kernel/workqueue.c:3254 [inline] process_scheduled_works+0x465/0x990 kernel/workqueue.c:3335 worker_thread+0x526/0x730 kernel/workqueue.c:3416 kthread+0x1d1/0x210 kernel/kthread.c:388 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 27 Comm: kworker/u8:1 Tainted: G W 6.8.0-syzkaller-08073-g480e035fc4c7 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024 Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet

Weakness

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

Affected Software

Extended Description

A race condition occurs within concurrent environments, and it is effectively a property of a code sequence. Depending on the context, a code sequence may be in the form of a function call, a small number of instructions, a series of program invocations, etc. A race condition violates these properties, which are closely related:

A race condition exists when an “interfering code sequence” can still access the shared resource, violating exclusivity. The interfering code sequence could be “trusted” or “untrusted.” A trusted interfering code sequence occurs within the product; it cannot be modified by the attacker, and it can only be invoked indirectly. An untrusted interfering code sequence can be authored directly by the attacker, and typically it is external to the vulnerable product.

Potential Mitigations

• Minimize the usage of shared resources in order to remove as much complexity as possible from the control flow and to reduce the likelihood of unexpected conditions occurring.
• Additionally, this will minimize the amount of synchronization necessary and may even help to reduce the likelihood of a denial of service where an attacker may be able to repeatedly trigger a critical section (CWE-400).

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/26.html
• https://cwe.mitre.org/data/definitions/29.html

References

• https://git.kernel.org/stable/c/2c02c5059c78a52d170bdee4a369b470de6deb37
• https://git.kernel.org/stable/c/68e84120319d4fc298fcdb14cf0bea6a0f64ffbd
• https://git.kernel.org/stable/c/6ebfad33161afacb3e1e59ed1c2feefef70f9f97
• https://git.kernel.org/stable/c/84c510411e321caff3c07e6cd0f917f06633cfc0
• https://git.kernel.org/stable/c/8b1e273c6afcf00d3c40a54ada7d6aac1b503b97
• https://git.kernel.org/stable/c/d35b62c224e70797f8a1c37fe9bc4b3e294b7560
• https://git.kernel.org/stable/c/ee413f30ec4fe94a0bdf32c8f042cb06fa913234
• https://git.kernel.org/stable/c/ef7eed7e11d23337310ecc2c014ecaeea52719c5
• https://git.kernel.org/stable/c/2c02c5059c78a52d170bdee4a369b470de6deb37
• https://git.kernel.org/stable/c/68e84120319d4fc298fcdb14cf0bea6a0f64ffbd
• https://git.kernel.org/stable/c/6ebfad33161afacb3e1e59ed1c2feefef70f9f97
• https://git.kernel.org/stable/c/84c510411e321caff3c07e6cd0f917f06633cfc0
• https://git.kernel.org/stable/c/8b1e273c6afcf00d3c40a54ada7d6aac1b503b97
• https://git.kernel.org/stable/c/d35b62c224e70797f8a1c37fe9bc4b3e294b7560
• https://git.kernel.org/stable/c/ee413f30ec4fe94a0bdf32c8f042cb06fa913234
• https://git.kernel.org/stable/c/ef7eed7e11d23337310ecc2c014ecaeea52719c5
• https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html