CVE-2023-54247
Unknown Unknown - Not Provided
Warning Suppression Fix for BPF BTF Type ID Handling in Linux Kernel

Publication date: 2025-12-30

Last updated on: 2025-12-30

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: bpf: Silence a warning in btf_type_id_size() syzbot reported a warning in [1] with the following stacktrace: WARNING: CPU: 0 PID: 5005 at kernel/bpf/btf.c:1988 btf_type_id_size+0x2d9/0x9d0 kernel/bpf/btf.c:1988 ... RIP: 0010:btf_type_id_size+0x2d9/0x9d0 kernel/bpf/btf.c:1988 ... Call Trace: <TASK> map_check_btf kernel/bpf/syscall.c:1024 [inline] map_create+0x1157/0x1860 kernel/bpf/syscall.c:1198 __sys_bpf+0x127f/0x5420 kernel/bpf/syscall.c:5040 __do_sys_bpf kernel/bpf/syscall.c:5162 [inline] __se_sys_bpf kernel/bpf/syscall.c:5160 [inline] __x64_sys_bpf+0x79/0xc0 kernel/bpf/syscall.c:5160 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd With the following btf [1] DECL_TAG 'a' type_id=4 component_idx=-1 [2] PTR '(anon)' type_id=0 [3] TYPE_TAG 'a' type_id=2 [4] VAR 'a' type_id=3, linkage=static and when the bpf_attr.btf_key_type_id = 1 (DECL_TAG), the following WARN_ON_ONCE in btf_type_id_size() is triggered: if (WARN_ON_ONCE(!btf_type_is_modifier(size_type) && !btf_type_is_var(size_type))) return NULL; Note that 'return NULL' is the correct behavior as we don't want a DECL_TAG type to be used as a btf_{key,value}_type_id even for the case like 'DECL_TAG -> STRUCT'. So there is no correctness issue here, we just want to silence warning. To silence the warning, I added DECL_TAG as one of kinds in btf_type_nosize() which will cause btf_type_id_size() returning NULL earlier without the warning. [1] https://lore.kernel.org/bpf/[email protected]/
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Meta Information
Published
2025-12-30
Last Modified
2025-12-30
Generated
2026-05-07
AI Q&A
2025-12-30
EPSS Evaluated
2026-05-05
NVD
CVE-2023-54247
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux kernel *
Helpful Resources
Exploitability
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability involves a warning triggered in the Linux kernel's BPF (Berkeley Packet Filter) subsystem, specifically in the function btf_type_id_size(). The warning occurs when a certain type (DECL_TAG) is used improperly as a key or value type ID in BPF maps, which is not correct usage. Although this does not cause correctness issues, it triggers a warning that needed to be silenced. The fix involved modifying the code to recognize DECL_TAG as a type that should return NULL earlier without issuing a warning, thus preventing unnecessary warnings during operation.


How can this vulnerability impact me? :

This vulnerability does not cause correctness or security issues but results in warnings being triggered in the kernel logs when certain BPF types are used improperly. These warnings could potentially clutter logs or cause confusion during debugging or system monitoring. The fix silences these warnings to improve system stability and clarity but does not impact system security or functionality directly.


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