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Date: Tue, 27 Feb 2024 19:47:34 +0100 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-cve-announce@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org> Subject: CVE-2021-46974: bpf: Fix masking negation logic upon negative dst register Description =========== In the Linux kernel, the following vulnerability has been resolved: bpf: Fix masking negation logic upon negative dst register The negation logic for the case where the off_reg is sitting in the dst register is not correct given then we cannot just invert the add to a sub or vice versa. As a fix, perform the final bitwise and-op unconditionally into AX from the off_reg, then move the pointer from the src to dst and finally use AX as the source for the original pointer arithmetic operation such that the inversion yields a correct result. The single non-AX mov in between is possible given constant blinding is retaining it as it's not an immediate based operation. The Linux kernel CVE team has assigned CVE-2021-46974 to this issue. Affected and fixed versions =========================== Issue introduced in 4.14.113 with commit 12462c88e6e2 and fixed in 4.14.233 with commit 4d542ddb88fb Issue introduced in 4.19.19 with commit eed84f94ff8d and fixed in 4.19.190 with commit 0e2dfdc74a7f Issue introduced in 5.0 with commit 979d63d50c0c and fixed in 5.4.117 with commit 53e0db429b37 Issue introduced in 5.0 with commit 979d63d50c0c and fixed in 5.10.35 with commit 2cfa537674cd Issue introduced in 5.0 with commit 979d63d50c0c and fixed in 5.11.19 with commit 6eba92a4d4be Issue introduced in 5.0 with commit 979d63d50c0c and fixed in 5.12.2 with commit 7cf64d8679ca Issue introduced in 5.0 with commit 979d63d50c0c and fixed in 5.13 with commit b9b34ddbe207 Please see https://www.kernel.org or 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-2021-46974 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/4d542ddb88fb2f39bf7f14caa2902f3e8d06f6ba https://git.kernel.org/stable/c/0e2dfdc74a7f4036127356d42ea59388f153f42c https://git.kernel.org/stable/c/53e0db429b37a32b8fc706d0d90eb4583ad13848 https://git.kernel.org/stable/c/2cfa537674cd1051a3b8111536d77d0558f33d5d https://git.kernel.org/stable/c/6eba92a4d4be8feb4dc33976abac544fa99d6ecc https://git.kernel.org/stable/c/7cf64d8679ca1cb20cf57d6a88bfee79a0922a66 https://git.kernel.org/stable/c/b9b34ddbe2076ade359cd5ce7537d5ed019e9807
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