{"cve":"CVE-2021-47390","nvd":{"published":"2024-05-21T15:15:24.397","modified":"2026-08-04T10:17:01.297","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: x86: Fix stack-out-of-bounds memory access from ioapic_write_indirect()\n\nKASAN reports the following issue:\n\n BUG: KASAN: stack-out-of-bounds in kvm_make_vcpus_request_mask+0x174/0x440 [kvm]\n Read of size 8 at addr ffffc9001364f638 by task qemu-kvm/4798\n\n CPU: 0 PID: 4798 Comm: qemu-kvm Tainted: G               X --------- ---\n Hardware name: AMD Corporation DAYTONA_X/DAYTONA_X, BIOS RYM0081C 07/13/2020\n Call Trace:\n  dump_stack+0xa5/0xe6\n  print_address_description.constprop.0+0x18/0x130\n  ? kvm_make_vcpus_request_mask+0x174/0x440 [kvm]\n  __kasan_report.cold+0x7f/0x114\n  ? kvm_make_vcpus_request_mask+0x174/0x440 [kvm]\n  kasan_report+0x38/0x50\n  kasan_check_range+0xf5/0x1d0\n  kvm_make_vcpus_request_mask+0x174/0x440 [kvm]\n  kvm_make_scan_ioapic_request_mask+0x84/0xc0 [kvm]\n  ? kvm_arch_exit+0x110/0x110 [kvm]\n  ? sched_clock+0x5/0x10\n  ioapic_write_indirect+0x59f/0x9e0 [kvm]\n  ? static_obj+0xc0/0xc0\n  ? __lock_acquired+0x1d2/0x8c0\n  ? kvm_ioapic_eoi_inject_work+0x120/0x120 [kvm]\n\nThe problem appears to be that 'vcpu_bitmap' is allocated as a single long\non stack and it should really be KVM_MAX_VCPUS long. We also seem to clear\nthe lower 16 bits of it with bitmap_zero() for no particular reason (my\nguess would be that 'bitmap' and 'vcpu_bitmap' variables in\nkvm_bitmap_or_dest_vcpus() caused the confusion: while the later is indeed\n16-bit long, the later should accommodate all possible vCPUs).","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H","score":7.1},"cwes":["CWE-125"],"references":["https://git.kernel.org/stable/c/2f9b68f57c6278c322793a06063181deded0ad69","https://git.kernel.org/stable/c/99a9e9b80f19fc63be005a33d76211dd23114792","https://git.kernel.org/stable/c/bebabb76ad9acca8858e0371e102fb60d708e25b","https://git.kernel.org/stable/c/2f9b68f57c6278c322793a06063181deded0ad69","https://git.kernel.org/stable/c/99a9e9b80f19fc63be005a33d76211dd23114792"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:50:30.954589733+00:00"},"epss":{"cve":"CVE-2021-47390","score":0.00262,"percentile":0.18036,"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."]}