CVE-2023-52621

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

bpf: Check rcu_read_lock_trace_held() before calling bpf map helpers

These three bpf_map_{lookup,update,delete}_elem() helpers are also available for sleepable bpf program, so add the corresponding lock assertion for sleepable bpf program, otherwise the following warning will be reported when a sleepable bpf program manipulates bpf map under interpreter mode (aka bpf_jit_enable=0):

WARNING: CPU: 3 PID: 4985 at kernel/bpf/helpers.c:40 …… CPU: 3 PID: 4985 Comm: test_progs Not tainted 6.6.0+ #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) …… RIP: 0010:bpf_map_lookup_elem+0x54/0x60 …… Call Trace: ? __warn+0xa5/0x240 ? bpf_map_lookup_elem+0x54/0x60 ? report_bug+0x1ba/0x1f0 ? handle_bug+0x40/0x80 ? exc_invalid_op+0x18/0x50 ? asm_exc_invalid_op+0x1b/0x20 ? __pfx_bpf_map_lookup_elem+0x10/0x10 ? rcu_lockdep_current_cpu_online+0x65/0xb0 ? rcu_is_watching+0x23/0x50 ? bpf_map_lookup_elem+0x54/0x60 ? __pfx_bpf_map_lookup_elem+0x10/0x10 ___bpf_prog_run+0x513/0x3b70 __bpf_prog_run32+0x9d/0xd0 ? __bpf_prog_enter_sleepable_recur+0xad/0x120 ? __bpf_prog_enter_sleepable_recur+0x3e/0x120 bpf_trampoline_6442580665+0x4d/0x1000 __x64_sys_getpgid+0x5/0x30 ? do_syscall_64+0x36/0xb0 entry_SYSCALL_64_after_hwframe+0x6e/0x76

Weakness

The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.

Affected Software

Extended Description

While assertion is good for catching logic errors and reducing the chances of reaching more serious vulnerability conditions, it can still lead to a denial of service. For example, if a server handles multiple simultaneous connections, and an assert() occurs in one single connection that causes all other connections to be dropped, this is a reachable assertion that leads to a denial of service.

Potential Mitigations

References

• https://git.kernel.org/stable/c/169410eba271afc9f0fb476d996795aa26770c6d
• https://git.kernel.org/stable/c/483cb92334cd7f1d5387dccc0ab5d595d27a669d
• https://git.kernel.org/stable/c/c7f1b6146f4a46d727c0d046284c28b6882c6304
• https://git.kernel.org/stable/c/d6d6fe4bb105595118f12abeed4a7bdd450853f3
• https://git.kernel.org/stable/c/169410eba271afc9f0fb476d996795aa26770c6d
• https://git.kernel.org/stable/c/483cb92334cd7f1d5387dccc0ab5d595d27a669d
• https://git.kernel.org/stable/c/c7f1b6146f4a46d727c0d046284c28b6882c6304
• https://git.kernel.org/stable/c/d6d6fe4bb105595118f12abeed4a7bdd450853f3