# CVE-2024-47702: bpf: Fail verification for sign-extension of packet data/data_end/data_meta

CVE-2024-47702 is fixed in 26 products on 1 platform, first by DEBIAN-CVE-2024-47702, released October 21, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2024-47702
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0021
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 21, 2024
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-47702

## Description

In the Linux kernel, the following vulnerability has been resolved:  bpf: Fail verification for sign-extension of packet data/data_end/data_meta  syzbot reported a kernel crash due to   commit 1f1e864b6555 ("bpf: Handle sign-extenstin ctx member accesses"). The reason is due to sign-extension of 32-bit load for packet data/data_end/data_meta uapi field.  The original code looks like:         r2 = *(s32 *)(r1 + 76) /* load __sk_buff->data */         r3 = *(u32 *)(r1 + 80) /* load __sk_buff->data_end */         r0 = r2         r0 += 8         if r3 > r0 goto +1         ... Note that __sk_buff->data load has 32-bit sign extension.  After verification and convert_ctx_accesses(), the final asm code looks like:         r2 = *(u64 *)(r1 +208)         r2 = (s32)r2         r3 = *(u64 *)(r1 +80)         r0 = r2         r0 += 8         if r3 > r0 goto pc+1         ... Note that 'r2 = (s32)r2' may make the kernel __sk_buff->data address invalid which may cause runtime failure.  Currently, in C code, typically we have         void *data = (void *)(long)skb->data;         void *data_end = (void *)(long)skb->data_end;         ... and it will generate         r2 = *(u64 *)(r1 +208)         r3 = *(u64 *)(r1 +80)         r0 = r2         r0 += 8         if r3 > r0 goto pc+1  If we allow sign-extension,         void *data = (void *)(long)(int)skb->data;         void *data_end = (void *)(long)skb->data_end;         ... the generated code looks like         r2 = *(u64 *)(r1 +208)         r2 <<= 32         r2 s>>= 32         r3 = *(u64 *)(r1 +80)         r0 = r2         r0 += 8         if r3 > r0 goto pc+1 and this will cause verification failure since "r2 <<= 32" is not allowed as "r2" is a packet pointer.  To fix this issue for case   r2 = *(s32 *)(r1 + 76) /* load __sk_buff->data */ this patch added additional checking in is_valid_access() callback function for packet data/data_end/data_meta access. If those accesses are with sign-extenstion, the verification will fail.    [1] https://lore.kernel.org/bpf/000000000000c90eee061d236d37@google.com/

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | dtb-aarch64 opensuse-leap 15.6 | 6.4.0-150600.23.30.1 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-64kb opensuse-leap 15.6 | 6.4.0-150600.23.30.1 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-64kb sles 15.6 | 6.4.0-150600.23.30.1 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-azure opensuse-leap 15.6 | 6.4.0-150600.8.17.2 | [SUSE-SU-2024:3984-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3984-1.md) | Nov 13, 2024 |
| Linux | kernel-azure sles 15.6 | 6.4.0-150600.8.17.2 | [SUSE-SU-2024:3984-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3984-1.md) | Nov 13, 2024 |
| Linux | kernel-coco sles 15.6 | 6.4.0-15061.9.coco15sp6.1 | [SUSE-SU-2024:4387-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4387-1.md) | Dec 19, 2024 |
| Linux | kernel-coco_debug sles 15.6 | 6.4.0-15061.9.coco15sp6.1 | [SUSE-SU-2024:4387-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4387-1.md) | Dec 19, 2024 |
| Linux | kernel-debug opensuse-leap 15.6 | 6.4.0-150600.23.30.1 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-default opensuse-leap 15.6 | 6.4.0-150600.23.30.1 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-default sles 15.6 | 6.4.0-150600.23.30.1 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-default-base opensuse-leap 15.6 | 6.4.0-150600.23.30.1.150600.12.12.6 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-default-base sles 15.6 | 6.4.0-150600.23.30.1.150600.12.12.6 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-docs opensuse-leap 15.6 | 6.4.0-150600.23.30.1 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-docs sles 15.6 | 6.4.0-150600.23.30.1 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-kvmsmall opensuse-leap 15.6 | 6.4.0-150600.23.30.1 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-livepatch-SLE15-SP6-RT_Update_5 sles 15.6 | 1-150600.1.3.1 | [SUSE-SU-2024:3986-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3986-1.md) | Nov 13, 2024 |
| Linux | kernel-livepatch-SLE15-SP6_Update_6 sles 15.6 | 1-150600.13.3.5 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-obs-build opensuse-leap 15.6 | 6.4.0-150600.23.30.1 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-obs-build sles 15.6 | 6.4.0-150600.23.30.1 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-obs-qa opensuse-leap 15.6 | 6.4.0-150600.23.30.1 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-rt opensuse-leap 15.6 | 6.4.0-150600.10.17.1 | [SUSE-SU-2024:3986-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3986-1.md) | Nov 13, 2024 |
| Linux | kernel-rt_debug opensuse-leap 15.6 | 6.4.0-150600.10.17.1 | [SUSE-SU-2024:3986-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3986-1.md) | Nov 13, 2024 |
| Linux | kernel-source opensuse-leap 15.6 | 6.4.0-150600.23.30.1 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-source sles 15.6 | 6.4.0-150600.23.30.1 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-source-azure opensuse-leap 15.6 | 6.4.0-150600.8.17.1 | [SUSE-SU-2024:3984-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3984-1.md) | Nov 13, 2024 |
| Linux | kernel-source-azure sles 15.6 | 6.4.0-150600.8.17.1 | [SUSE-SU-2024:3984-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3984-1.md) | Nov 13, 2024 |
| Linux | kernel-source-coco sles 15.6 | 6.4.0-15061.9.coco15sp6.1 | [SUSE-SU-2024:4387-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4387-1.md) | Dec 19, 2024 |
| Linux | kernel-source-rt opensuse-leap 15.6 | 6.4.0-150600.10.17.1 | [SUSE-SU-2024:3986-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3986-1.md) | Nov 13, 2024 |
| Linux | kernel-syms opensuse-leap 15.6 | 6.4.0-150600.23.30.1 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-syms sles 15.6 | 6.4.0-150600.23.30.1 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-syms-azure opensuse-leap 15.6 | 6.4.0-150600.8.17.1 | [SUSE-SU-2024:3984-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3984-1.md) | Nov 13, 2024 |
| Linux | kernel-syms-azure sles 15.6 | 6.4.0-150600.8.17.1 | [SUSE-SU-2024:3984-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3984-1.md) | Nov 13, 2024 |
| Linux | kernel-syms-coco sles 15.6 | 6.4.0-15061.9.coco15sp6.1 | [SUSE-SU-2024:4387-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4387-1.md) | Dec 19, 2024 |
| Linux | kernel-syms-rt opensuse-leap 15.6 | 6.4.0-150600.10.17.1 | [SUSE-SU-2024:3986-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-3986-1.md) | Nov 13, 2024 |
| Linux | kernel-zfcpdump opensuse-leap 15.6 | 6.4.0-150600.23.30.1 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | kernel-zfcpdump sles 15.6 | 6.4.0-150600.23.30.1 | [SUSE-SU-2024:4318-1](https://patchblox.com/security/data/fix/linux/suse-su-2024-4318-1.md) | Dec 13, 2024 |
| Linux | linux Debian 13.5 (trixie) | 6.11.2-1 | [DEBIAN-CVE-2024-47702](https://patchblox.com/security/data/fix/linux/debian-cve-2024-47702.md) | Oct 21, 2024 |
| Linux | linux Debian 14 | 6.11.2-1 | [DEBIAN-CVE-2024-47702](https://patchblox.com/security/data/fix/linux/debian-cve-2024-47702.md) | Oct 21, 2024 |

---

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