{ "schema_version": "1.6.1", "id": "RPI-CVE-2024-26983", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2024-26983" ], "published": "2024-05-01T05:31:05Z", "summary": "bootconfig: use memblock_free_late to free xbc memory to buddy", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbootconfig: use memblock_free_late to free xbc memory to buddy\n\nOn the time to free xbc memory in xbc_exit(), memblock may has handed\nover memory to buddy allocator. So it doesn't make sense to free memory\nback to memblock. memblock_free() called by xbc_exit() even causes UAF bugs\non architectures with CONFIG_ARCH_KEEP_MEMBLOCK disabled like x86.\nFollowing KASAN logs shows this case.\n\nThis patch fixes the xbc memory free problem by calling memblock_free()\nin early xbc init error rewind path and calling memblock_free_late() in\nxbc exit path to free memory to buddy allocator.\n\n[ 9.410890] ==================================================================\n[ 9.418962] BUG: KASAN: use-after-free in memblock_isolate_range+0x12d/0x260\n[ 9.426850] Read of size 8 at addr ffff88845dd30000 by task swapper/0/1\n\n[ 9.435901] CPU: 9 PID: 1 Comm: swapper/0 Tainted: G U 6.9.0-rc3-00208-g586b5dfb51b9 #5\n[ 9.446403] Hardware name: Intel Corporation RPLP LP5 (CPU:RaptorLake)/RPLP LP5 (ID:13), BIOS IRPPN02.01.01.00.00.19.015.D-00000000 Dec 28 2023\n[ 9.460789] Call Trace:\n[ 9.463518] \n[ 9.465859] dump_stack_lvl+0x53/0x70\n[ 9.469949] print_report+0xce/0x610\n[ 9.473944] ? __virt_addr_valid+0xf5/0x1b0\n[ 9.478619] ? memblock_isolate_range+0x12d/0x260\n[ 9.483877] kasan_report+0xc6/0x100\n[ 9.487870] ? memblock_isolate_range+0x12d/0x260\n[ 9.493125] memblock_isolate_range+0x12d/0x260\n[ 9.498187] memblock_phys_free+0xb4/0x160\n[ 9.502762] ? __pfx_memblock_phys_free+0x10/0x10\n[ 9.508021] ? mutex_unlock+0x7e/0xd0\n[ 9.512111] ? __pfx_mutex_unlock+0x10/0x10\n[ 9.516786] ? kernel_init_freeable+0x2d4/0x430\n[ 9.521850] ? __pfx_kernel_init+0x10/0x10\n[ 9.526426] xbc_exit+0x17/0x70\n[ 9.529935] kernel_init+0x38/0x1e0\n[ 9.533829] ? _raw_spin_unlock_irq+0xd/0x30\n[ 9.538601] ret_from_fork+0x2c/0x50\n[ 9.542596] ? __pfx_kernel_init+0x10/0x10\n[ 9.547170] ret_from_fork_asm+0x1a/0x30\n[ 9.551552] \n\n[ 9.555649] The buggy address belongs to the physical page:\n[ 9.561875] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x45dd30\n[ 9.570821] flags: 0x200000000000000(node=0|zone=2)\n[ 9.576271] page_type: 0xffffffff()\n[ 9.580167] raw: 0200000000000000 ffffea0011774c48 ffffea0012ba1848 0000000000000000\n[ 9.588823] raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000\n[ 9.597476] page dumped because: kasan: bad access detected\n\n[ 9.605362] Memory state around the buggy address:\n[ 9.610714] ffff88845dd2ff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00\n[ 9.618786] ffff88845dd2ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00\n[ 9.626857] >ffff88845dd30000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff\n[ 9.634930] ^\n[ 9.638534] ffff88845dd30080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff\n[ 9.646605] ffff88845dd30100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff\n[ 9.654675] ==================================================================", "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": [ 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"1:6.6.28-1+rpt1" }, { "binary_name": "linux-image-6.6.28+rpt-rpi-v8", "binary_version": "1:6.6.28-1+rpt1" } ] }, "database_specific": { "per_version": { "1:6.1.21-1+rpt1": { "linux_commit": "0afb5e98488aed7017b9bf321b575d0177feb7ed", "upstream_version": "6.1.21", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.88" }, "1:6.1.47-1+rpt2": { "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e", "upstream_version": "6.1.47", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.88" }, "1:6.1.47-1+rpt4": { "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e", "upstream_version": "6.1.47", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.88", "compiled_filter": false }, "1:6.1.54-1+rpt2": { "linux_commit": "2906f7abdc03d4a92b6b0e2e0c87ea2a9dffe8f7", "upstream_version": "6.1.54", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.88" }, "1:6.1.58-1+rpt2": { "linux_commit": "ccf1586ad0663fa91238ac56abf6340d6d740d18", "upstream_version": "6.1.58", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.1.88" }, "1:6.1.63-1+rpt1": { "linux_commit": null, "upstream_version": "6.1.63", "assessment": "upstream version (no usable Linux commit)", "upstream_fixed": "6.1.88" }, "1:6.1.73-1+rpt1": { "linux_commit": null, "upstream_version": "6.1.73", "assessment": "upstream version (no usable Linux commit)", "upstream_fixed": "6.1.88" }, "1:6.6.20-1+rpt1": { "linux_commit": "6f16847710cc0502450788b9f12f0a14d3429668", "upstream_version": "6.6.20", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.6.29" }, "1:6.6.28-1+rpt1": { "linux_commit": "0c341f47adc3578cd5f817aa20ee2b7f9ae6b23e", "upstream_version": "6.6.28", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.6.29" } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2024-26983" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/1e7feb31a18c197d63a5e606025ed63c762f8918" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/e46d3be714ad9652480c6db129ab8125e2d20ab7" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/5a7dfb8fcd3f29fc93161100179b27f24f3d5f35" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/89f9a1e876b5a7ad884918c03a46831af202c8a0" } ], "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 defect lives in `__init` boot path code (`kernel_init()` \u2192 `exit_boot_config()` \u2192 `xbc_exit()`) and in memblock teardown; there is no network, adjacent-network, or remote-peer data path of any kind, and reaching it requires being present on the local machine as it boots. Local is the highest defensible vector for boot-time-only code.\nAC:L - Once `CONFIG_BOOT_CONFIG` is enabled (Kconfig recommends \"say Y\") and a bootconfig is supplied via initrd/cmdline, embedded blob, or `BOOT_CONFIG_FORCE`, the use-after-free occurs on every boot with no race, timing window, or memory-layout condition to win \u2014 x86's default `!CONFIG_ARCH_KEEP_MEMBLOCK` guarantees `memblock_discard()` has already released `memblock.reserved.regions` to buddy before `kernel_init()` runs.\nPR:L - There is no runtime privilege gate on this path at all because it executes in the `kernel_init` thread before any userspace process exists; PR:L is selected as the higher-severity of the plausible local options rather than PR:H, even though arranging the bootconfig itself would require bootloader/initrd control.\nUI:N - No victim action such as mounting a filesystem, opening a device, or plugging in hardware is involved \u2014 `exit_boot_config()` is invoked unconditionally by the kernel itself in `kernel_init()`.\nS:U - Both the faulting code and the corrupted memory are kernel-owned; no VM, IOMMU, hypervisor, or sandbox boundary is crossed.\nC:H - This is a confirmed use-after-free (KASAN \"Read of size 8\" in `memblock_isolate_range`) against pages already handed to the buddy allocator and reallocated to arbitrary kernel consumers; the freed contents are consumed as region bounds that steer subsequent writes, and corrupting a reallocated page-table or slab page during boot is a plausible route to kernel memory disclosure.\nI:H - The path does not merely read freed memory \u2014 `memblock_isolate_range()` writes `rgn->base`/`rgn->size`, `memblock_insert_region()` and `memblock_remove_region()` `memmove()` region structs, and the empty-array case zeroes `regions[0]`, all into buddy-owned pages that other kernel subsystems are actively using, silently corrupting live kernel state with values derived from the bootconfig allocations' physical geometry.\nA:H - Writing memblock region structures over reallocated live kernel memory during boot produces oopses/panics \u2014 KASAN reports it immediately, and without KASAN the corrupted page tables, slab objects, or task structures cause crash-class failures that can render the system unbootable." } } }