{ "schema_version": "1.6.1", "id": "RPI-CVE-2024-26884", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2024-26884" ], "published": "2024-04-17T10:29:01Z", "summary": "bpf: Fix hashtab overflow check on 32-bit arches", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix hashtab overflow check on 32-bit arches\n\nThe hashtab code relies on roundup_pow_of_two() to compute the number of\nhash buckets, and contains an overflow check by checking if the\nresulting value is 0. However, on 32-bit arches, the roundup code itself\ncan overflow by doing a 32-bit left-shift of an unsigned long value,\nwhich is undefined behaviour, so it is not guaranteed to truncate\nneatly. This was triggered by syzbot on the DEVMAP_HASH type, which\ncontains the same check, copied from the hashtab code. So apply the same\nfix to hashtab, by moving the overflow check to before the roundup.", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.1.21-1+rpt1", "1:6.1.47-1+rpt2", "1:6.1.47-1+rpt4", "1:6.1.54-1+rpt2", "1:6.1.58-1+rpt2", "1:6.1.63-1+rpt1", "1:6.1.73-1+rpt1", "1:6.6.20-1+rpt1" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.1.0-rpi1-rpi-v6", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v7", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v7l", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v8", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v6", "binary_version": "1:6.1.47-1+rpt2" }, { "binary_name": "linux-image-6.1.0-rpi2-rpi-v7", "binary_version": 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"assessment": "upstream version (no usable Linux commit)", "upstream_fixed": "6.1.83" }, "1:6.1.73-1+rpt1": { "linux_commit": null, "upstream_version": "6.1.73", "assessment": "upstream version (no usable Linux commit)", "upstream_fixed": "6.1.83" }, "1:6.6.20-1+rpt1": { "linux_commit": "6f16847710cc0502450788b9f12f0a14d3429668", "upstream_version": "6.6.20", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.6.23" } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2024-26884" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/33ec04cadb77605b71d9298311919303d390c4d5" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/92c81fbb3ed2e0dfc33a4183a67135e1ab566ace" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/64f00b4df0597590b199b62a37a165473bf658a6" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/3b08cfc65f07b1132c1979d73f014ae6e04de55d" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/a83fdaeaea3677b83a53f72ace2d73a19bcd6d93" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/8435f0961bf3dc65e204094349bd9aeaac1f8868" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/d817f0d34d927f2deb17dadbfe212c9a6a32ac3e" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/a6fa75b5096c0f9826a4fabe22d907b0a5bb1016" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/6787d916c2cf9850c97a0a3f73e08c43e7d973b1" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-05T11:52:36Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 7.8, "cvss_v3_severity": "High", "scenario": "AV:L - The vulnerability is reached purely through the bpf(2) syscall \u2014 BPF_MAP_CREATE with an oversized max_entries followed by BPF_MAP_UPDATE_ELEM. No network or physical access is involved.\nAC:L - Exploitation is fully deterministic: one map-create with max_entries > 0x80000000 and one map-update, with no race, no timing window and no memory-layout condition outside the attacker's control. The 32-bit-arch requirement is a property of the target platform (ARM32/x86-32/MIPS32 dominate embedded, IoT, automotive and Android-era devices running these stable branches), not a condition the attacker must win.\nPR:L - BPF_MAP_TYPE_HASH/PERCPU_HASH/HASH_OF_MAPS sit in the explicitly \"unprivileged\" branch of map_create()'s privilege switch, requiring no CAP_BPF; the only gate is sysctl_unprivileged_bpf_disabled, which defaults to 0 on the affected 4.19/5.4/5.10 branches and on any build without CONFIG_BPF_UNPRIV_DEFAULT_OFF. A plain local user account therefore suffices.\nUI:N - The attacker performs the entire sequence themselves via two syscalls; no victim action, mount, or file open is needed.\nS:U - The corruption and its effects are confined to kernel memory within the same security authority; no hypervisor, IOMMU or sandbox boundary is crossed.\nC:H - A bogus n_buckets that escapes the overflow check leaves htab->buckets as a zero-sized ZERO_SIZE_PTR allocation while __select_bucket() indexes it with an unmasked, key-derived 32-bit offset, so lookups read and dereference attacker-chosen out-of-bounds kernel memory, yielding an arbitrary-read primitive.\nI:H - The same wild bucket pointer is written through by htab_lock_bucket() (raw_spinlock acquire) and hlist_nulls_add_head_rcu() during map update, giving an out-of-bounds write of kernel list pointers at an attacker-influenced offset \u2014 a corruption primitive suitable for control-flow hijack.\nA:H - The identical pattern was demonstrated by syzbot as a kernel crash on arm32, and even the benign UB outcome (n_buckets == 1 with a ~4-billion entry limit) forces unbounded hash-chain walks under a raw spinlock with IRQs disabled, producing hard lockups, RCU stalls and panics." } } }