{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2023-53645", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2023-53645", "idYear": 2023, "status": "PUBLISHED", "publishedAt": "2025-10-07T15:19:43.738Z", "updatedAt": "2026-08-05T09:15:20.081Z", "importedAt": "2026-10-24T01:57:03.413Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "bpf: Make bpf_refcount_acquire fallible for non-owning refs", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Make bpf_refcount_acquire fallible for non-owning refs\n\nThis patch fixes an incorrect assumption made in the original\nbpf_refcount series [0], specifically that the BPF program calling\nbpf_refcount_acquire on some node can always guarantee that the node is\nalive. In that series, the patch adding failure behavior to rbtree_add\nand list_push_{front, back} breaks this assumption for non-owning\nreferences.\n\nConsider the following program:\n\n n = bpf_kptr_xchg(&mapval, NULL);\n /* skip error checking */\n\n bpf_spin_lock(&l);\n if(bpf_rbtree_add(&t, &n->rb, less)) {\n bpf_refcount_acquire(n);\n /* Failed to add, do something else with the node */\n }\n bpf_spin_unlock(&l);\n\nIt's incorrect to assume that bpf_refcount_acquire will always succeed in this\nscenario. bpf_refcount_acquire is being called in a critical section\nhere, but the lock being held is associated with rbtree t, which isn't\nnecessarily the lock associated with the tree that the node is already\nin. So after bpf_rbtree_add fails to add the node and calls bpf_obj_drop\nin it, the program has no ownership of the node's lifetime. Therefore\nthe node's refcount can be decr'd to 0 at any time after the failing\nrbtree_add. If this happens before the refcount_acquire above, the node\nmight be free'd, and regardless refcount_acquire will be incrementing a\n0 refcount.\n\nLater patches in the series exercise this scenario, resulting in the\nexpected complaint from the kernel (without this patch's changes):\n\n refcount_t: addition on 0; use-after-free.\n WARNING: CPU: 1 PID: 207 at lib/refcount.c:25 refcount_warn_saturate+0xbc/0x110\n Modules linked in: bpf_testmod(O)\n CPU: 1 PID: 207 Comm: test_progs Tainted: G O 6.3.0-rc7-02231-g723de1a718a2-dirty #371\n Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.15.0-0-g2dd4b9b3f840-prebuilt.qemu.org 04/01/2014\n RIP: 0010:refcount_warn_saturate+0xbc/0x110\n Code: 6f 64 f6 02 01 e8 84 a3 5c ff 0f 0b eb 9d 80 3d 5e 64 f6 02 00 75 94 48 c7 c7 e0 13 d2 82 c6 05 4e 64 f6 02 01 e8 64 a3 5c ff <0f> 0b e9 7a ff ff ff 80 3d 38 64 f6 02 00 0f 85 6d ff ff ff 48 c7\n RSP: 0018:ffff88810b9179b0 EFLAGS: 00010082\n RAX: 0000000000000000 RBX: 0000000000000002 RCX: 0000000000000000\n RDX: 0000000000000202 RSI: 0000000000000008 RDI: ffffffff857c3680\n RBP: ffff88810027d3c0 R08: ffffffff8125f2a4 R09: ffff88810b9176e7\n R10: ffffed1021722edc R11: 746e756f63666572 R12: ffff88810027d388\n R13: ffff88810027d3c0 R14: ffffc900005fe030 R15: ffffc900005fe048\n FS: 00007fee0584a700(0000) GS:ffff88811b280000(0000) knlGS:0000000000000000\n CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n CR2: 00005634a96f6c58 CR3: 0000000108ce9002 CR4: 0000000000770ee0\n DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\n DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\n PKRU: 55555554\n Call Trace:\n \n bpf_refcount_acquire_impl+0xb5/0xc0\n\n (rest of output snipped)\n\nThe patch addresses this by changing bpf_refcount_acquire_impl to use\nrefcount_inc_not_zero instead of refcount_inc and marking\nbpf_refcount_acquire KF_RET_NULL.\n\nFor owning references, though, we know the above scenario is not possible\nand thus that bpf_refcount_acquire will always succeed. Some verifier\nbookkeeping is added to track \"is input owning ref?\" for bpf_refcount_acquire\ncalls and return false from is_kfunc_ret_null for bpf_refcount_acquire on\nowning refs despite it being marked KF_RET_NULL.\n\nExisting selftests using bpf_refcount_acquire are modified where\nnecessary to NULL-check its return value.\n\n [0]: https://lore.kernel.org/bpf/20230415201811.343116-1-davemarchevsky@fb.com/", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "d2dcc67df910dd85253a701b6a5b747f955d28f5", "status": "affected", "versionType": "git", "lessThan": "d906d1b940b9dbf0a3e821d6b32a51c369273d91" }, { "version": "d2dcc67df910dd85253a701b6a5b747f955d28f5", "status": "affected", "versionType": "git", "lessThan": "7793fc3babe9fea908e57f7c187ea819f9fd7e95" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "6.4", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "6.4" }, { "version": "6.4.4", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.4.*" }, { "version": "6.5", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }