CVE-2026-46279
In the Linux kernel, the following vulnerability has been resolved: mm/alloc_tag: clear codetag for pages allocated before page_ext initialization Due to initialization ordering, page_ext is allocated and initialized relatively late during boot. Some pages have already been allocated and freed before page_ext becomes available, leaving their codetag uninitialized. A clear example is in init_section_page_ext(): alloc_page_ext() calls kmemleak_alloc(). If the slab cache has no free objects, it falls back to the buddy allocator to allocate memory. However, at this point page_ext is not yet fully initialized, so these newly allocated pages have no codetag set. These pages may later be reclaimed by KASAN, which causes the warning to trigger when they are freed because their codetag ref is still empty. Use a global array to track pages allocated before page_ext is fully initialized. The array size is fixed at 8192 entries, and will emit a warning if this limit is exceeded. When page_ext initialization completes, set their codetag to empty to avoid warnings when they are freed later. This warning is only observed with CONFIG_MEM_ALLOC_PROFILING_DEBUG=Y and mem_profiling_compressed disabled: [ 9.582133] ------------[ cut here ]------------ [ 9.582137] alloc_tag was not set [ 9.582139] WARNING: ./include/linux/alloc_tag.h:164 at __pgalloc_tag_sub+0x40f/0x550, CPU#5: systemd/1 [ 9.582190] CPU: 5 UID: 0 PID: 1 Comm: systemd Not tainted 7.0.0-rc4 #1 PREEMPT(lazy) [ 9.582192] Hardware name: Red Hat KVM, BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 [ 9.582194] RIP: 0010:__pgalloc_tag_sub+0x40f/0x550 [ 9.582196] Code: 00 00 4c 29 e5 48 8b 05 1f 88 56 05 48 8d 4c ad 00 48 8d 2c c8 e9 87 fd ff ff 0f 0b 0f 0b e9 f3 fe ff ff 48 8d 3d 61 2f ed 03 <67> 48 0f b9 3a e9 b3 fd ff ff 0f 0b eb e4 e8 5e cd 14 02 4c 89 c7 [ 9.582197] RSP: 0018:ffffc9000001f940 EFLAGS: 00010246 [ 9.582200] RAX: dffffc0000000000 RBX: 1ffff92000003f2b RCX: 1ffff110200d806c [ 9.582201] RDX: ffff8881006c0360 RSI: 0000000000000004 RDI: ffffffff9bc7b460 [ 9.582202] RBP: 0000000000000000 R08: 0000000000000000 R09: fffffbfff3a62324 [ 9.582203] R10: ffffffff9d311923 R11: 0000000000000000 R12: ffffea0004001b00 [ 9.582204] R13: 0000000000002000 R14: ffffea0000000000 R15: ffff8881006c0360 [ 9.582206] FS: 00007ffbbcf2d940(0000) GS:ffff888450479000(0000) knlGS:0000000000000000 [ 9.582208] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 9.582210] CR2: 000055ee3aa260d0 CR3: 0000000148b67005 CR4: 0000000000770ef0 [ 9.582211] PKRU: 55555554 [ 9.582212] Call Trace: [ 9.582213] <TASK> [ 9.582214] ? __pfx___pgalloc_tag_sub+0x10/0x10 [ 9.582216] ? check_bytes_and_report+0x68/0x140 [ 9.582219] __free_frozen_pages+0x2e4/0x1150 [ 9.582221] ? __free_slab+0xc2/0x2b0 [ 9.582224] qlist_free_all+0x4c/0xf0 [ 9.582227] kasan_quarantine_reduce+0x15d/0x180 [ 9.582229] __kasan_slab_alloc+0x69/0x90 [ 9.582232] kmem_cache_alloc_noprof+0x14a/0x500 [ 9.582234] do_getname+0x96/0x310 [ 9.582237] do_readlinkat+0x91/0x2f0 [ 9.582239] ? __pfx_do_readlinkat+0x10/0x10 [ 9.582240] ? get_random_bytes_user+0x1df/0x2c0 [ 9.582244] __x64_sys_readlinkat+0x96/0x100 [ 9.582246] do_syscall_64+0xce/0x650 [ 9.582250] ? __x64_sys_getrandom+0x13a/0x1e0 [ 9.582252] ? __pfx___x64_sys_getrandom+0x10/0x10 [ 9.582254] ? do_syscall_64+0x114/0x650 [ 9.582255] ? ksys_read+0xfc/0x1d0 [ 9.582258] ? __pfx_ksys_read+0x10/0x10 [ 9.582260] ? do_syscall_64+0x114/0x650 [ 9.582262] ? do_syscall_64+0x114/0x650 [ 9.582264] ? __pfx_fput_close_sync+0x10/0x10 [ 9.582266] ? file_close_fd_locked+0x178/0x2a0 [ 9.582268] ? __x64_sys_faccessat2+0x96/0x100 [ 9.582269] ? __x64_sys_close+0x7d/0xd0 [ 9.582271] ? do_syscall_64+0x114/0x650 [ 9.582273] ? do_syscall_64+0x114/0x650 [ 9.582275] ? clear_bhb_loop+0x50/0xa0 [ 9.582277] ? clear_bhb_l ---truncated---
Executive briefing
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Evidence confidence: Not assessed Evidence-derived, not an exploitability verdict
Severity & attack characteristics
CVSS vector:CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
No CVSS vector is currently available in the source record.
Technical explanation & impact
Technical root-cause details are not available in the current source record.
Assess the impact using the published CVSS metrics and the affected vendor component.
Affected products and versions
NVD has not supplied machine-readable vulnerable CPE product/version entries for this CVE. This is an information gap, not proof that no products are affected. Check the vendor advisory references below.
Remediation & validation
- Identify exposure by comparing the affected product and version ranges with your asset inventory, SBOM and externally exposed services.
- Review the linked vendor security advisory or patch notes. Upgrade to a vendor-confirmed fixed release; do not infer a fixed version from the CVE description.
- Until patched, consider restricting network access or disabling the affected feature where operationally safe. These are temporary controls, not a substitute for a vendor fix.
- Validate the remediation with a version check and vulnerability rescan, then retain change evidence.
No fixed version is displayed unless it is explicitly established by a vendor advisory. Follow the vendor's release notes for exact product and branch applicability.