| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2023-52928: bpf: Skip invalid kfunc call in backtrack_insn |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| bpf: Skip invalid kfunc call in backtrack_insn |
| |
| The verifier skips invalid kfunc call in check_kfunc_call(), which |
| would be captured in fixup_kfunc_call() if such insn is not eliminated |
| by dead code elimination. However, this can lead to the following |
| warning in backtrack_insn(), also see [1]: |
| |
| ------------[ cut here ]------------ |
| verifier backtracking bug |
| WARNING: CPU: 6 PID: 8646 at kernel/bpf/verifier.c:2756 backtrack_insn |
| kernel/bpf/verifier.c:2756 |
| __mark_chain_precision kernel/bpf/verifier.c:3065 |
| mark_chain_precision kernel/bpf/verifier.c:3165 |
| adjust_reg_min_max_vals kernel/bpf/verifier.c:10715 |
| check_alu_op kernel/bpf/verifier.c:10928 |
| do_check kernel/bpf/verifier.c:13821 [inline] |
| do_check_common kernel/bpf/verifier.c:16289 |
| [...] |
| |
| So make backtracking conservative with this by returning ENOTSUPP. |
| |
| [1] https://lore.kernel.org/bpf/CACkBjsaXNceR8ZjkLG=dT3P=4A8SBsg0Z5h5PWLryF5=ghKq=g@mail.gmail.com/ |
| |
| The Linux kernel CVE team has assigned CVE-2023-52928 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 5.15.93 with commit 6e2fac197de2c4c041bdd8982cffb104689113f1 |
| Fixed in 6.1.11 with commit 74eec8266f37aff609db6a2f2b093e56a11c28c4 |
| Fixed in 6.2 with commit d3178e8a434b58678d99257c0387810a24042fb6 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2023-52928 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| kernel/bpf/verifier.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/6e2fac197de2c4c041bdd8982cffb104689113f1 |
| https://git.kernel.org/stable/c/74eec8266f37aff609db6a2f2b093e56a11c28c4 |
| https://git.kernel.org/stable/c/d3178e8a434b58678d99257c0387810a24042fb6 |
