CVE-2022-49228 bpf: Fix a btf decl_tag bug when tagging a function

What is CVE-2022-49228?

CVE-2022-49228 is a medium-severity vulnerability in Linux kernel, published on 26 Feb 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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

bpf: Fix a btf decl_tag bug when tagging a function

syzbot reported a btf decl_tag bug with stack trace below:

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 0 PID: 3592 Comm: syz-executor914 Not tainted 5.16.0-syzkaller-11424-gb7892f7d5cb2 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:btf_type_vlen include/linux/btf.h:231 [inline] RIP: 0010:btf_decl_tag_resolve+0x83e/0xaa0 kernel/bpf/btf.c:3910 ... Call Trace: <TASK> btf_resolve+0x251/0x1020 kernel/bpf/btf.c:4198 btf_check_all_types kernel/bpf/btf.c:4239 [inline] btf_parse_type_sec kernel/bpf/btf.c:4280 [inline] btf_parse kernel/bpf/btf.c:4513 [inline] btf_new_fd+0x19fe/0x2370 kernel/bpf/btf.c:6047 bpf_btf_load kernel/bpf/syscall.c:4039 [inline] __sys_bpf+0x1cbb/0x5970 kernel/bpf/syscall.c:4679 __do_sys_bpf kernel/bpf/syscall.c:4738 [inline] __se_sys_bpf kernel/bpf/syscall.c:4736 [inline] __x64_sys_bpf+0x75/0xb0 kernel/bpf/syscall.c:4736 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae

The kasan error is triggered with an illegal BTF like below: type 0: void type 1: int type 2: decl_tag to func type 3 type 3: func to func_proto type 8 The total number of types is 4 and the type 3 is illegal since its func_proto type is out of range.

Currently, the target type of decl_tag can be struct/union, var or func. Both struct/union and var implemented their own 'resolve' callback functions and hence handled properly in kernel. But func type doesn't have 'resolve' callback function. When btf_decl_tag_resolve() tries to check func type, it tries to get vlen of its func_proto type, which triggered the above kasan error.

To fix the issue, btf_decl_tag_resolve() needs to do btf_func_check() before trying to accessing func_proto type. In the current implementation, func type is checked with btf_func_check() in the main checking function btf_check_all_types(). To fix the above kasan issue, let us implement 'resolve' callback func type properly. The 'resolve' callback will be also called in btf_check_all_types() for func types.

Weakness: CWE-476

Which versions are affected by CVE-2022-49228?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2022-49228?

Apply the vendor's patch.

Is CVE-2022-49228 being exploited?

There is no known exploitation of CVE-2022-49228 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2022-49228, GHSA-xx7j-2fqw-vv47, UBUNTU-CVE-2022-49228.