# CVE-2025-38517: linux: In the Linux kernel, the following vulnerability has been resolved: lib/alloc_tag: do not acquire non-existent lock... CVE-2025-38517 is fixed in 23 products on 1 platform, first by ALAS2023-2025-1145, released August 8, 2025. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2025-38517 - Priority: Routine - CVSS: 5.5 (medium) - EPSS: 0.0016 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Aug 8, 2025 ## Description In the Linux kernel, the following vulnerability has been resolved: lib/alloc_tag: do not acquire non-existent lock in alloc_tag_top_users() alloc_tag_top_users() attempts to lock alloc_tag_cttype->mod_lock even when the alloc_tag_cttype is not allocated because: 1) alloc tagging is disabled because mem profiling is disabled (!alloc_tag_cttype) 2) alloc tagging is enabled, but not yet initialized (!alloc_tag_cttype) 3) alloc tagging is enabled, but failed initialization (!alloc_tag_cttype or IS_ERR(alloc_tag_cttype)) In all cases, alloc_tag_cttype is not allocated, and therefore alloc_tag_top_users() should not attempt to acquire the semaphore. This leads to a crash on memory allocation failure by attempting to acquire a non-existent semaphore: Oops: general protection fault, probably for non-canonical address 0xdffffc000000001b: 0000 [#3] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x00000000000000d8-0x00000000000000df] CPU: 2 UID: 0 PID: 1 Comm: systemd Tainted: G D 6.16.0-rc2 #1 VOLUNTARY Tainted: [D]=DIE Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:down_read_trylock+0xaa/0x3b0 Code: d0 7c 08 84 d2 0f 85 a0 02 00 00 8b 0d df 31 dd 04 85 c9 75 29 48 b8 00 00 00 00 00 fc ff df 48 8d 6b 68 48 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 88 02 00 00 48 3b 5b 68 0f 85 53 01 00 00 65 ff RSP: 0000:ffff8881002ce9b8 EFLAGS: 00010016 RAX: dffffc0000000000 RBX: 0000000000000070 RCX: 0000000000000000 RDX: 000000000000001b RSI: 000000000000000a RDI: 0000000000000070 RBP: 00000000000000d8 R08: 0000000000000001 R09: ffffed107dde49d1 R10: ffff8883eef24e8b R11: ffff8881002cec20 R12: 1ffff11020059d37 R13: 00000000003fff7b R14: ffff8881002cec20 R15: dffffc0000000000 FS: 00007f963f21d940(0000) GS:ffff888458ca6000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f963f5edf71 CR3: 000000010672c000 CR4: 0000000000350ef0 Call Trace: codetag_trylock_module_list+0xd/0x20 alloc_tag_top_users+0x369/0x4b0 __show_mem+0x1cd/0x6e0 warn_alloc+0x2b1/0x390 __alloc_frozen_pages_noprof+0x12b9/0x21a0 alloc_pages_mpol+0x135/0x3e0 alloc_slab_page+0x82/0xe0 new_slab+0x212/0x240 ___slab_alloc+0x82a/0xe00 As David Wang points out, this issue became easier to trigger after commit 780138b12381 ("alloc_tag: check mem_profiling_support in alloc_tag_init"). Before the commit, the issue occurred only when it failed to allocate and initialize alloc_tag_cttype or if a memory allocation fails before alloc_tag_init() is called. After the commit, it can be easily triggered when memory profiling is compiled but disabled at boot. To properly determine whether alloc_tag_init() has been called and its data structures initialized, verify that alloc_tag_cttype is a valid pointer before acquiring the semaphore. If the variable is NULL or an error value, it has not been properly initialized. In such a case, just skip and do not attempt to acquire the semaphore. [harry.yoo@oracle.com: v3] ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | bpftool6.12 amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | bpftool6.12-debuginfo amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | kernel-livepatch-6.12.40-63.114 amzn 2023 | 1:1.0-0.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | kernel6.12 amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | kernel6.12-debuginfo amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | kernel6.12-debuginfo-common-aarch64 amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | kernel6.12-debuginfo-common-x86_64 amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | kernel6.12-devel amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | kernel6.12-headers amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | kernel6.12-libbpf amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | kernel6.12-libbpf-debuginfo amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | kernel6.12-libbpf-devel amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | kernel6.12-libbpf-static amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | kernel6.12-modules-extra amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | kernel6.12-modules-extra-common amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | kernel6.12-tools amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | kernel6.12-tools-debuginfo amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | kernel6.12-tools-devel amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | linux Debian 13.5 (trixie) | 6.12.41-1 | [DEBIAN-CVE-2025-38517](https://patchblox.com/security/data/fix/linux/debian-cve-2025-38517.md) | Aug 16, 2025 | | Linux | linux Debian 14 | 6.16.3-1 | [DEBIAN-CVE-2025-38517](https://patchblox.com/security/data/fix/linux/debian-cve-2025-38517.md) | Aug 16, 2025 | | Linux | perf6.12 amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | perf6.12-debuginfo amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | python3-perf6.12 amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | | Linux | python3-perf6.12-debuginfo amzn 2023 | 1:6.12.40-63.114.amzn2023 | [ALAS2023-2025-1145](https://patchblox.com/security/data/fix/linux/alas2023-2025-1145.md) | Aug 8, 2025 | --- Data as of 2026-11-08T13:06:02Z UTC. 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