bpf: Prevent decl_tag from being referenced in func_proto arg

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Prevent decl_tag from being referenced in func_proto arg Syzkaller managed to hit another decl_tag issue: btf_func_proto_check kernel/bpf/btf.c:4506 [inline] btf_check_all_types kernel/bpf/btf.c:4734 [inline] btf_parse_type_sec+0x1175/0x1980 kernel/bpf/btf.c:4763 btf_parse kernel/bpf/btf.c:5042 [inline] btf_new_fd+0x65a/0xb00 kernel/bpf/btf.c:6709 bpf_btf_load+0x6f/0x90 kernel/bpf/syscall.c:4342 __sys_bpf+0x50a/0x6c0 kernel/bpf/syscall.c:5034 __do_sys_bpf kernel/bpf/syscall.c:5093 [inline] __se_sys_bpf kernel/bpf/syscall.c:5091 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5091 do_syscall_64+0x54/0x70 arch/x86/entry/common.c:48 This seems similar to commit ea68376c8bed ("bpf: prevent decl_tag from being referenced in func_proto") but for the argument.

References

• https://git.kernel.org/stable/c/3f3d54962a032581996edda8e6bcbf7a30371234
• https://git.kernel.org/stable/c/e6d276dcc9204f95632580c43d66c52ca502d7ec
• https://git.kernel.org/stable/c/f17472d4599697d701aa239b4c475a506bccfd19