{"cve":"CVE-2022-48845","nvd":{"published":"2024-07-16T13:15:11.803","modified":"2026-06-17T05:16:21.883","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nMIPS: smp: fill in sibling and core maps earlier\n\nAfter enabling CONFIG_SCHED_CORE (landed during 5.14 cycle),\n2-core 2-thread-per-core interAptiv (CPS-driven) started emitting\nthe following:\n\n[    0.025698] CPU1 revision is: 0001a120 (MIPS interAptiv (multi))\n[    0.048183] ------------[ cut here ]------------\n[    0.048187] WARNING: CPU: 1 PID: 0 at kernel/sched/core.c:6025 sched_core_cpu_starting+0x198/0x240\n[    0.048220] Modules linked in:\n[    0.048233] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.17.0-rc3+ #35 b7b319f24073fd9a3c2aa7ad15fb7993eec0b26f\n[    0.048247] Stack : 817f0000 00000004 327804c8 810eb050 00000000 00000004 00000000 c314fdd1\n[    0.048278]         830cbd64 819c0000 81800000 817f0000 83070bf4 00000001 830cbd08 00000000\n[    0.048307]         00000000 00000000 815fcbc4 00000000 00000000 00000000 00000000 00000000\n[    0.048334]         00000000 00000000 00000000 00000000 817f0000 00000000 00000000 817f6f34\n[    0.048361]         817f0000 818a3c00 817f0000 00000004 00000000 00000000 4dc33260 0018c933\n[    0.048389]         ...\n[    0.048396] Call Trace:\n[    0.048399] [<8105a7bc>] show_stack+0x3c/0x140\n[    0.048424] [<8131c2a0>] dump_stack_lvl+0x60/0x80\n[    0.048440] [<8108b5c0>] __warn+0xc0/0xf4\n[    0.048454] [<8108b658>] warn_slowpath_fmt+0x64/0x10c\n[    0.048467] [<810bd418>] sched_core_cpu_starting+0x198/0x240\n[    0.048483] [<810c6514>] sched_cpu_starting+0x14/0x80\n[    0.048497] [<8108c0f8>] cpuhp_invoke_callback_range+0x78/0x140\n[    0.048510] [<8108d914>] notify_cpu_starting+0x94/0x140\n[    0.048523] [<8106593c>] start_secondary+0xbc/0x280\n[    0.048539]\n[    0.048543] ---[ end trace 0000000000000000 ]---\n[    0.048636] Synchronize counters for CPU 1: done.\n\n...for each but CPU 0/boot.\nBasic debug printks right before the mentioned line say:\n\n[    0.048170] CPU: 1, smt_mask:\n\nSo smt_mask, which is sibling mask obviously, is empty when entering\nthe function.\nThis is critical, as sched_core_cpu_starting() calculates\ncore-scheduling parameters only once per CPU start, and it's crucial\nto have all the parameters filled in at that moment (at least it\nuses cpu_smt_mask() which in fact is `&cpu_sibling_map[cpu]` on\nMIPS).\n\nA bit of debugging led me to that set_cpu_sibling_map() performing\nthe actual map calculation, was being invocated after\nnotify_cpu_start(), and exactly the latter function starts CPU HP\ncallback round (sched_core_cpu_starting() is basically a CPU HP\ncallback).\nWhile the flow is same on ARM64 (maps after the notifier, although\nbefore calling set_cpu_online()), x86 started calculating sibling\nmaps earlier than starting the CPU HP callbacks in Linux 4.14 (see\n[0] for the reference). Neither me nor my brief tests couldn't find\nany potential caveats in calculating the maps right after performing\ndelay calibration, but the WARN splat is now gone.\nThe very same debug prints now yield exactly what I expected from\nthem:\n\n[    0.048433] CPU: 1, smt_mask: 0-1\n\n[0] https://git.kernel.org/pub/scm/linux/kernel/git/mips/linux.git/commit/?id=76ce7cfe35ef","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/32813321f18d5432cec1b1a6ecc964f9ea26d565","https://git.kernel.org/stable/c/56eaacb8137ba2071ce48d4e3d91979270e139a7","https://git.kernel.org/stable/c/7315f8538db009605ffba00370678142ef00ac98","https://git.kernel.org/stable/c/94647aec80d03d6914aa664b7b8e103cd9d63239","https://git.kernel.org/stable/c/be538b764a46be1d0700fd3b6e82fb76bd17f13a"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:52:42.518321223+00:00"},"epss":{"cve":"CVE-2022-48845","score":0.00225,"percentile":0.13255,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}