| 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-2021-47317: powerpc/bpf: Fix detecting BPF atomic instructions |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| powerpc/bpf: Fix detecting BPF atomic instructions |
| |
| Commit 91c960b0056672 ("bpf: Rename BPF_XADD and prepare to encode other |
| atomics in .imm") converted BPF_XADD to BPF_ATOMIC and added a way to |
| distinguish instructions based on the immediate field. Existing JIT |
| implementations were updated to check for the immediate field and to |
| reject programs utilizing anything more than BPF_ADD (such as BPF_FETCH) |
| in the immediate field. |
| |
| However, the check added to powerpc64 JIT did not look at the correct |
| BPF instruction. Due to this, such programs would be accepted and |
| incorrectly JIT'ed resulting in soft lockups, as seen with the atomic |
| bounds test. Fix this by looking at the correct immediate value. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47317 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.12 with commit 91c960b0056672e74627776655c926388350fa30 and fixed in 5.12.19 with commit 7284dab07e4d51d453cc42851fae9ec4fac6ef2f |
| Issue introduced in 5.12 with commit 91c960b0056672e74627776655c926388350fa30 and fixed in 5.13.4 with commit 0d435b6d94b05dcfd836d758a63145aa566618e2 |
| Issue introduced in 5.12 with commit 91c960b0056672e74627776655c926388350fa30 and fixed in 5.14 with commit 419ac821766cbdb9fd85872bb3f1a589df05c94c |
| |
| 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-2021-47317 |
| 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: |
| arch/powerpc/net/bpf_jit_comp64.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/7284dab07e4d51d453cc42851fae9ec4fac6ef2f |
| https://git.kernel.org/stable/c/0d435b6d94b05dcfd836d758a63145aa566618e2 |
| https://git.kernel.org/stable/c/419ac821766cbdb9fd85872bb3f1a589df05c94c |
