CVE-2022-50536

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

bpf, sockmap: Fix repeated calls to sock_put() when msg has more_data

In tcp_bpf_send_verdict() redirection, the eval variable is assigned to __SK_REDIRECT after the apply_bytes data is sent, if msg has more_data, sock_put() will be called multiple times.

We should reset the eval variable to __SK_NONE every time more_data starts.

This causes:

IPv4: Attempt to release TCP socket in state 1 00000000b4c925d7 ————[ cut here ]———— refcount_t: addition on 0; use-after-free. WARNING: CPU: 5 PID: 4482 at lib/refcount.c:25 refcount_warn_saturate+0x7d/0x110 Modules linked in: CPU: 5 PID: 4482 Comm: sockhash_bypass Kdump: loaded Not tainted 6.0.0 #1 Hardware name: Red Hat KVM, BIOS 1.11.0-2.el7 04/01/2014 Call Trace: __tcp_transmit_skb+0xa1b/0xb90 ? __alloc_skb+0x8c/0x1a0 ? __kmalloc_node_track_caller+0x184/0x320 tcp_write_xmit+0x22a/0x1110 __tcp_push_pending_frames+0x32/0xf0 do_tcp_sendpages+0x62d/0x640 tcp_bpf_push+0xae/0x2c0 tcp_bpf_sendmsg_redir+0x260/0x410 ? preempt_count_add+0x70/0xa0 tcp_bpf_send_verdict+0x386/0x4b0 tcp_bpf_sendmsg+0x21b/0x3b0 sock_sendmsg+0x58/0x70 __sys_sendto+0xfa/0x170 ? xfd_validate_state+0x1d/0x80 ? switch_fpu_return+0x59/0xe0 __x64_sys_sendto+0x24/0x30 do_syscall_64+0x37/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Affected Software

References

• https://git.kernel.org/stable/c/113236e8f49f262f318c00ebb14b15f4834e87c1
• https://git.kernel.org/stable/c/28e4a763cd4a2b1a78852216ef4bd7df3a05cec6
• https://git.kernel.org/stable/c/578a7628b838a3ac8ad61deaab5a816ff032ac13
• https://git.kernel.org/stable/c/7508b9f4daac4ec7dfe0b6fb2d688b1c1c105e10
• https://git.kernel.org/stable/c/7a9841ca025275b5b0edfb0b618934abb6ceec15
• https://git.kernel.org/stable/c/8786bde11a4f31b63b3036731df0b47337a7a245