{"id":"AZL-51300","summary":"CVE-2024-47716 affecting package kernel for versions less than 6.6.56.1-5","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nARM: 9410/1: vfp: Use asm volatile in fmrx/fmxr macros\n\nFloating point instructions in userspace can crash some arm kernels\nbuilt with clang/LLD 17.0.6:\n\n    BUG: unsupported FP instruction in kernel mode\n    FPEXC == 0xc0000780\n    Internal error: Oops - undefined instruction: 0 [#1] ARM\n    CPU: 0 PID: 196 Comm: vfp-reproducer Not tainted 6.10.0 #1\n    Hardware name: BCM2835\n    PC is at vfp_support_entry+0xc8/0x2cc\n    LR is at do_undefinstr+0xa8/0x250\n    pc : [\u003cc0101d50\u003e]    lr : [\u003cc010a80c\u003e]    psr: a0000013\n    sp : dc8d1f68  ip : 60000013  fp : bedea19c\n    r10: ec532b17  r9 : 00000010  r8 : 0044766c\n    r7 : c0000780  r6 : ec532b17  r5 : c1c13800  r4 : dc8d1fb0\n    r3 : c10072c4  r2 : c0101c88  r1 : ec532b17  r0 : 0044766c\n    Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none\n    Control: 00c5387d  Table: 0251c008  DAC: 00000051\n    Register r0 information: non-paged memory\n    Register r1 information: vmalloc memory\n    Register r2 information: non-slab/vmalloc memory\n    Register r3 information: non-slab/vmalloc memory\n    Register r4 information: 2-page vmalloc region\n    Register r5 information: slab kmalloc-cg-2k\n    Register r6 information: vmalloc memory\n    Register r7 information: non-slab/vmalloc memory\n    Register r8 information: non-paged memory\n    Register r9 information: zero-size pointer\n    Register r10 information: vmalloc memory\n    Register r11 information: non-paged memory\n    Register r12 information: non-paged memory\n    Process vfp-reproducer (pid: 196, stack limit = 0x61aaaf8b)\n    Stack: (0xdc8d1f68 to 0xdc8d2000)\n    1f60:                   0000081f b6f69300 0000000f c10073f4 c10072c4 dc8d1fb0\n    1f80: ec532b17 0c532b17 0044766c b6f9ccd8 00000000 c010a80c 00447670 60000010\n    1fa0: ffffffff c1c13800 00c5387d c0100f10 b6f68af8 00448fc0 00000000 bedea188\n    1fc0: bedea314 00000001 00448ebc b6f9d000 00447608 b6f9ccd8 00000000 bedea19c\n    1fe0: bede9198 bedea188 b6e1061c 0044766c 60000010 ffffffff 00000000 00000000\n    Call trace:\n    [\u003cc0101d50\u003e] (vfp_support_entry) from [\u003cc010a80c\u003e] (do_undefinstr+0xa8/0x250)\n    [\u003cc010a80c\u003e] (do_undefinstr) from [\u003cc0100f10\u003e] (__und_usr+0x70/0x80)\n    Exception stack(0xdc8d1fb0 to 0xdc8d1ff8)\n    1fa0:                                     b6f68af8 00448fc0 00000000 bedea188\n    1fc0: bedea314 00000001 00448ebc b6f9d000 00447608 b6f9ccd8 00000000 bedea19c\n    1fe0: bede9198 bedea188 b6e1061c 0044766c 60000010 ffffffff\n    Code: 0a000061 e3877202 e594003c e3a09010 (eef16a10)\n    ---[ end trace 0000000000000000 ]---\n    Kernel panic - not syncing: Fatal exception in interrupt\n    ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---\n\nThis is a minimal userspace reproducer on a Raspberry Pi Zero W:\n\n    #include \u003cstdio.h\u003e\n    #include \u003cmath.h\u003e\n\n    int main(void)\n    {\n            double v = 1.0;\n            printf(\"%fn\", NAN + *(volatile double *)&v);\n            return 0;\n    }\n\nAnother way to consistently trigger the oops is:\n\n    calvin@raspberry-pi-zero-w ~$ python -c \"import json\"\n\nThe bug reproduces only when the kernel is built with DYNAMIC_DEBUG=n,\nbecause the pr_debug() calls act as barriers even when not activated.\n\nThis is the output from the same kernel source built with the same\ncompiler and DYNAMIC_DEBUG=y, where the userspace reproducer works as\nexpected:\n\n    VFP: bounce: trigger ec532b17 fpexc c0000780\n    VFP: emulate: INST=0xee377b06 SCR=0x00000000\n    VFP: bounce: trigger eef1fa10 fpexc c0000780\n    VFP: emulate: INST=0xeeb40b40 SCR=0x00000000\n    VFP: raising exceptions 30000000\n\n    calvin@raspberry-pi-zero-w ~$ ./vfp-reproducer\n    nan\n\nCrudely grepping for vmsr/vmrs instructions in the otherwise nearly\nidential text for vfp_support_entry() makes the problem obvious:\n\n    vmlinux.llvm.good [0xc0101cb8] \u003c+48\u003e:  vmrs   r7, fpexc\n    vmlinux.llvm.good [0xc0101cd8] \u003c+80\u003e:  vmsr   fpexc, r0\n    vmlinux.llvm.good [0xc0101d20\n---truncated---","modified":"2026-04-01T05:17:42.531472Z","published":"2024-10-21T12:15:07Z","upstream":["CVE-2024-47716"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-47716"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.56.1-5"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-51300.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}