{"id":"CVE-2024-47702","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fail verification for sign-extension of packet data/data_end/data_meta\n\nsyzbot reported a kernel crash due to\n  commit 1f1e864b6555 (\"bpf: Handle sign-extenstin ct…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fail verification for sign-extension of packet data/data_end/data_meta\n\nsyzbot reported a kernel crash due to\n  commit 1f1e864b6555 (\"bpf: Handle sign-extenstin ct…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 6.6, < 6.10.13","linux_kernel >= 6.11, < 6.11.2"],"patched":["linux_kernel 6.11.2"],"published":"2024-10-21","updated":"2026-10-03","sourceUpdated":"2026-10-03T11:17:31.513","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2024-47702","references":[{"url":"https://git.kernel.org/stable/c/4b48228eebce2ab1b01e3133da822164472b7e46","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/92de36080c93296ef9005690705cba260b9bd68a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f09757fe97a225ae505886eac572e4cbfba96537","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f1620c93a1ec950d87ef327a565d3907736d3340","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2024-10-21T13:04:24.861686Z"},"epss":0.00213,"epssPercentile":0.10532,"ingestedAt":"2026-10-03T11:43:42.103Z","slug":"CVE-2024-47702","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fail verification for sign-extension of packet data/data_end/data_meta\n\nsyzbot reported a kernel crash due to\n  commit 1f1e864b6555 (\"bpf: Handle sign-extenstin ctx member accesses\").\nThe reason is due to sign-extension of 32-bit load for\npacket data/data_end/data_meta uapi field.\n\nThe original code looks like:\n        r2 = *(s32 *)(r1 + 76) /* load __sk_buff->data */\n        r3 = *(u32 *)(r1 + 80) /* load __sk_buff->data_end */\n        r0 = r2\n        r0 += 8\n        if r3 > r0 goto +1\n        ...\nNote that __sk_buff->data load has 32-bit sign extension.\n\nAfter verification and convert_ctx_accesses(), the final asm code looks like:\n        r2 = *(u64 *)(r1 +208)\n        r2 = (s32)r2\n        r3 = *(u64 *)(r1 +80)\n        r0 = r2\n        r0 += 8\n        if r3 > r0 goto pc+1\n        ...\nNote that 'r2 = (s32)r2' may make the kernel __sk_buff->data address invalid\nwhich may cause runtime failure.\n\nCurrently, in C code, typically we have\n        void *data = (void *)(long)skb->data;\n        void *data_end = (void *)(long)skb->data_end;\n        ...\nand it will generate\n        r2 = *(u64 *)(r1 +208)\n        r3 = *(u64 *)(r1 +80)\n        r0 = r2\n        r0 += 8\n        if r3 > r0 goto pc+1\n\nIf we allow sign-extension,\n        void *data = (void *)(long)(int)skb->data;\n        void *data_end = (void *)(long)skb->data_end;\n        ...\nthe generated code looks like\n        r2 = *(u64 *)(r1 +208)\n        r2 <<= 32\n        r2 s>>= 32\n        r3 = *(u64 *)(r1 +80)\n        r0 = r2\n        r0 += 8\n        if r3 > r0 goto pc+1\nand this will cause verification failure since \"r2 <<= 32\" is not allowed\nas \"r2\" is a packet pointer.\n\nTo fix this issue for case\n  r2 = *(s32 *)(r1 + 76) /* load __sk_buff->data */\nthis patch added additional checking in is_valid_access() callback\nfunction for packet data/data_end/data_meta access. If those accesses\nare with sign-extenstion, the verification will fail.\n\n  [1] https://lore.kernel.org/bpf/000000000000c90eee061d236d37@google.com/\n\n## Affected\n\n- `linux_kernel >= 6.6, < 6.10.13`\n- `linux_kernel >= 6.11, < 6.11.2`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.11.2`","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}