{ "schema_version": "1.6.1", "id": "RPI-CVE-2026-46250", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2026-46250" ], "published": "2026-06-03T15:49:47Z", "summary": "MIPS: Work around LLVM bug when gp is used as global register variable", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nMIPS: Work around LLVM bug when gp is used as global register variable\n\nOn MIPS, __current_thread_info is defined as global register variable\nlocating in $gp, and is simply assigned with new address during kernel\nrelocation.\n\nThis however is broken with LLVM, which always restores $gp if it finds\n$gp is clobbered in any form, including when intentionally through a\nglobal register variable. This is against GCC's documentation[1], which\nrequires a callee-saved register used as global register variable not to\nbe restored if it's clobbered.\n\nAs a result, $gp will continue to point to the unrelocated kernel after\nthe epilog of relocate_kernel(), leading to an early crash in init_idle,\n\n[ 0.000000] CPU 0 Unable to handle kernel paging request at virtual address 0000000000000000, epc == ffffffff81afada8, ra == ffffffff81afad90\n[ 0.000000] Oops[#1]:\n[ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper Tainted: G W 6.19.0-rc5-00262-gd3eeb99bbc99-dirty #188 VOLUNTARY\n[ 0.000000] Tainted: [W]=WARN\n[ 0.000000] Hardware name: loongson,loongson64v-4core-virtio\n[ 0.000000] $ 0 : 0000000000000000 0000000000000000 0000000000000001 0000000000000000\n[ 0.000000] $ 4 : ffffffff80b80ec0 ffffffff80b53d48 0000000000000000 00000000000f4240\n[ 0.000000] $ 8 : 0000000000000100 ffffffff81d82f80 ffffffff81d82f80 0000000000000001\n[ 0.000000] $12 : 0000000000000000 ffffffff81776f58 00000000000005da 0000000000000002\n[ 0.000000] $16 : ffffffff80b80e40 0000000000000000 ffffffff80b81614 9800000005dfbe80\n[ 0.000000] $20 : 00000000540000e0 ffffffff81980000 0000000000000000 ffffffff80f81c80\n[ 0.000000] $24 : 0000000000000a26 ffffffff8114fb90\n[ 0.000000] $28 : ffffffff80b50000 ffffffff80b53d40 0000000000000000 ffffffff81afad90\n[ 0.000000] Hi : 0000000000000000\n[ 0.000000] Lo : 0000000000000000\n[ 0.000000] epc : ffffffff81afada8 init_idle+0x130/0x270\n[ 0.000000] ra : ffffffff81afad90 init_idle+0x118/0x270\n[ 0.000000] Status: 540000e2\tKX SX UX KERNEL EXL\n[ 0.000000] Cause : 00000008 (ExcCode 02)\n[ 0.000000] BadVA : 0000000000000000\n[ 0.000000] PrId : 00006305 (ICT Loongson-3)\n[ 0.000000] Process swapper (pid: 0, threadinfo=(____ptrval____), task=(____ptrval____), tls=0000000000000000)\n[ 0.000000] Stack : 9800000005dfbf00 ffffffff8178e950 0000000000000000 0000000000000000\n[ 0.000000] 0000000000000000 ffffffff81970000 000000000000003f ffffffff810a6528\n[ 0.000000] 0000000000000001 9800000005dfbe80 9800000005dfbf00 ffffffff81980000\n[ 0.000000] ffffffff810a6450 ffffffff81afb6c0 0000000000000000 ffffffff810a2258\n[ 0.000000] ffffffff81d82ec8 ffffffff8198d010 ffffffff81b67e80 ffffffff8197dd98\n[ 0.000000] ffffffff81d81c80 ffffffff81930000 0000000000000040 0000000000000000\n[ 0.000000] 0000000000000000 0000000000000000 0000000000000000 0000000000000000\n[ 0.000000] 0000000000000000 000000000000009e ffffffff9fc01000 0000000000000000\n[ 0.000000] 0000000000000000 0000000000000000 0000000000000000 0000000000000000\n[ 0.000000] 0000000000000000 ffffffff81ae86dc ffffffff81b3c741 0000000000000002\n[ 0.000000] ...\n[ 0.000000] Call Trace:\n[ 0.000000] [] init_idle+0x130/0x270\n[ 0.000000] [] sched_init+0x5c8/0x6c0\n[ 0.000000] [] start_kernel+0x27c/0x7a8\n\nThis bug has been reported to LLVM[2] and affects version from (at\nleast) 18 to 21. Let's work around this by using inline assembly to\nassign $gp before a fix is widely available.", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.1.47-1+rpt4" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.1.0-rpi3-rpi-2712", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v6", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l", "binary_version": "1:6.1.47-1+rpt4" }, { "binary_name": "linux-image-6.1.0-rpi3-rpi-v8", "binary_version": "1:6.1.47-1+rpt4" } ] }, "database_specific": { "per_version": { "1:6.1.47-1+rpt4": { "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e", "upstream_version": "6.1.47", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.165", "compiled_filter": false } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2026-46250" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/05bff9b0ae095b2420cfebb4a96759a09334bec6" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/1fe3b402b1e97a1718df3be0a1d3eee20133e735" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/4dc65b40fb80c2020efbf139b9a38d30f9a37b92" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/c0155dee51b9f5f48aaf5c71cae005eb0e36521f" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/e3a6498a63394218561065a9a7a597a204f52f6a" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/561834f6d6f52b8a1791331e94b2aac753491d2a" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/9bc3b0ae5203aba650297fdf3e1e774125e423f2" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/30bfc2d6a1132a89a5f1c3b96c59cf3e4d076ea3" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-05T13:16:28Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 7.3, "cvss_v3_severity": "High", "scenario": "AV:L - The vulnerable code runs only during early boot in `relocate_kernel()` (`arch/mips/kernel/head.S` \u2192 `arch/mips/kernel/relocate.c`), before any network stack or syscall interface exists; the only way to reach it is to boot or reboot the MIPS system locally.\nAC:L - When the kernel is built with LLVM/Clang, `CONFIG_RELOCATABLE`, and KASLR relocation (`offset != 0`), LLVM deterministically restores `$gp` in the `relocate_kernel()` epilog, causing a reliable crash in `init_idle()` on every affected boot without races or attacker-uncontrollable timing.\nPR:N - Execution occurs in the pre-authentication boot path (PID 0 swapper during `start_kernel()` \u2192 `sched_init()` \u2192 `init_idle()`), before any user login or privilege checks; no attacker credentials are required at the time the bug triggers.\nUI:N - No victim user action is required beyond normal system power-on or reboot; the fault occurs automatically during kernel initialization on affected builds.\nS:U - Impact is confined to kernel boot failure on the same machine; there is no crossing of security boundaries such as VM escape, sandbox escape, or IOMMU bypass.\nC:L - The stale `$gp`/`__current_thread_info` causes `current` to resolve from the unrelocated `init_thread_union`, leading to dereferences of invalid kernel memory and limited kernel-address information exposure in the oops before the paging fault at address 0.\nI:L - Before the fatal fault, `init_idle()` performs writes through the mis-resolved `current` pointer (e.g., task state and scheduler fields), enabling limited unintended modification of kernel structures even though the immediate outcome is a crash rather than controlled code execution.\nA:H - The bug produces a kernel oops during early boot in `init_idle()` with \"Unable to handle kernel paging request at virtual address 0000000000000000\", preventing the system from completing initialization and rendering it unavailable." } } }