{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-40947", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-07-12T12:17:45.589Z", "datePublished": "2024-07-12T12:31:52.810Z", "dateUpdated": "2026-08-05T11:34:10.711Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:34:10.711Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nima: Avoid blocking in RCU read-side critical section\n\nA panic happens in ima_match_policy:\n\nBUG: unable to handle kernel NULL pointer dereference at 0000000000000010\nPGD 42f873067 P4D 0\nOops: 0000 [#1] SMP NOPTI\nCPU: 5 PID: 1286325 Comm: kubeletmonit.sh\nKdump: loaded Tainted: P\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996),\n BIOS 0.0.0 02/06/2015\nRIP: 0010:ima_match_policy+0x84/0x450\nCode: 49 89 fc 41 89 cf 31 ed 89 44 24 14 eb 1c 44 39\n 7b 18 74 26 41 83 ff 05 74 20 48 8b 1b 48 3b 1d\n f2 b9 f4 00 0f 84 9c 01 00 00 <44> 85 73 10 74 ea\n 44 8b 6b 14 41 f6 c5 01 75 d4 41 f6 c5 02 74 0f\nRSP: 0018:ff71570009e07a80 EFLAGS: 00010207\nRAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000200\nRDX: ffffffffad8dc7c0 RSI: 0000000024924925 RDI: ff3e27850dea2000\nRBP: 0000000000000000 R08: 0000000000000000 R09: ffffffffabfce739\nR10: ff3e27810cc42400 R11: 0000000000000000 R12: ff3e2781825ef970\nR13: 00000000ff3e2785 R14: 000000000000000c R15: 0000000000000001\nFS: 00007f5195b51740(0000)\nGS:ff3e278b12d40000(0000) knlGS:0000000000000000\nCS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 0000000000000010 CR3: 0000000626d24002 CR4: 0000000000361ee0\nDR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\nCall Trace:\n ima_get_action+0x22/0x30\n process_measurement+0xb0/0x830\n ? page_add_file_rmap+0x15/0x170\n ? alloc_set_pte+0x269/0x4c0\n ? prep_new_page+0x81/0x140\n ? simple_xattr_get+0x75/0xa0\n ? selinux_file_open+0x9d/0xf0\n ima_file_check+0x64/0x90\n path_openat+0x571/0x1720\n do_filp_open+0x9b/0x110\n ? page_counter_try_charge+0x57/0xc0\n ? files_cgroup_alloc_fd+0x38/0x60\n ? __alloc_fd+0xd4/0x250\n ? do_sys_open+0x1bd/0x250\n do_sys_open+0x1bd/0x250\n do_syscall_64+0x5d/0x1d0\n entry_SYSCALL_64_after_hwframe+0x65/0xca\n\nCommit c7423dbdbc9e (\"ima: Handle -ESTALE returned by\nima_filter_rule_match()\") introduced call to ima_lsm_copy_rule within a\nRCU read-side critical section which contains kmalloc with GFP_KERNEL.\nThis implies a possible sleep and violates limitations of RCU read-side\ncritical sections on non-PREEMPT systems.\n\nSleeping within RCU read-side critical section might cause\nsynchronize_rcu() returning early and break RCU protection, allowing a\nUAF to happen.\n\nThe root cause of this issue could be described as follows:\n|\tThread A\t|\tThread B\t|\n|\t\t\t|ima_match_policy\t|\n|\t\t\t| rcu_read_lock\t|\n|ima_lsm_update_rule\t|\t\t\t|\n| synchronize_rcu\t|\t\t\t|\n|\t\t\t| kmalloc(GFP_KERNEL)|\n|\t\t\t| sleep\t\t|\n==> synchronize_rcu returns early\n| kfree(entry)\t\t|\t\t\t|\n|\t\t\t| entry = entry->next|\n==> UAF happens and entry now becomes NULL (or could be anything).\n|\t\t\t| entry->action\t|\n==> Accessing entry might cause panic.\n\nTo fix this issue, we are converting all kmalloc that is called within\nRCU read-side critical section to use GFP_ATOMIC.\n\n[PM: fixed missing comment, long lines, !CONFIG_IMA_LSM_RULES case]" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable RCU read-side section is entered from `ima_file_check()`/`process_measurement()` on the `open()`/`execve()` path, so the attacker must be executing code locally on the host. There is no network protocol handler that reaches `ima_match_policy()` directly.\nAC:L - The attacker fully controls the reader side (an `open()` storm across all CPUs), the memory pressure that forces the `GFP_KERNEL` allocation into reclaim and schedules away, and the parallelism — no specific memory layout or timing the attacker cannot influence is needed, and `ima_lsm_update_rules()` performs a separate `synchronize_rcu()` for every LSM rule, leaving a wide window. The one precondition outside attacker control is a concurrent SELinux policy reload/`setsebool`, a routine administrative event the attacker can simply hold a persistent trigger loop through (and can even detect via the unprivileged-readable selinuxfs status page).\nPR:L - Reaching `ima_match_policy()` requires only the ability to open files as an ordinary unprivileged local user; there is no capability check anywhere on the `path_openat → ima_file_check → ima_match_policy` path. No root or CAP_MAC_ADMIN is needed on the attacker's side.\nUI:N - The race is hit entirely by the attacker's own threads sleeping inside the RCU read-side critical section; no victim has to open a file, mount a filesystem, or perform any action for the UAF to occur.\nS:U - The freed `ima_rule_entry` and all resulting corruption are within the host kernel's own security authority. This is standard in-kernel memory corruption with no VM, IOMMU, or sandbox boundary crossed.\nC:H - After the early `synchronize_rcu()` return, the reader dereferences the freed rule's `list.next`, `fsname` (passed to `strcmp()`), and `template` pointers, so a heap spray of the reallocated `ima_rule_entry` yields attacker-directed kernel reads. Per kernel scoring guidance, a use-after-free is treated as High confidentiality impact.\nI:H - `struct ima_rule_entry` holds four function pointers (`uid_op`, `gid_op`, `fowner_op`, `fgroup_op`) that `ima_match_rules()` calls directly, plus `template`, whose `fields[i]->field_init()` is invoked in `ima_api.c` — controlling the reallocated object gives control-flow hijack. The attacker can also forge `entry->action`/`entry->flags` to suppress IMA measurement and appraisal, defeating the integrity subsystem itself.\nA:H - The reported real-world symptom is a kernel NULL-pointer dereference and panic in `ima_match_policy+0x84/0x450` reached from `do_sys_open()`. Any use-after-free of this kind reliably oopses or panics the machine even when not exploited further." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/linux/lsm_hook_defs.h", "include/linux/security.h", "kernel/auditfilter.c", "security/apparmor/audit.c", "security/apparmor/include/audit.h", "security/integrity/ima/ima.h", "security/integrity/ima/ima_policy.c", "security/security.c", "security/selinux/include/audit.h", "security/selinux/ss/services.c", "security/smack/smack_lsm.c" ], "versions": [ { "version": "c4b035b1f036ddd53fbfced49046e586c5ad8a3e", "lessThan": "a6176a802c4bfb83bf7524591aa75f44a639a853", "status": "affected", "versionType": "git" }, { "version": "2d4bc60693c4206c64723e94ae5f7a04c0b8f18f", "lessThan": "a38e02265c681b51997a264aaf743095e2ee400a", "status": "affected", "versionType": "git" }, { "version": "8008f1691c15f353f5a53dc5d450b8262cb57421", "lessThan": "9c3906c3738562b1fedc6f1cfc81756a7cfefff0", "status": "affected", "versionType": "git" }, { "version": "c7423dbdbc9ecef7fff5239d144cad4b9887f4de", "lessThan": "28d0ecc52f6c927d0e9ba70a4f2c1ea15453ee88", "status": "affected", "versionType": "git" }, { "version": "c7423dbdbc9ecef7fff5239d144cad4b9887f4de", "lessThan": "58275455893066149e9f4df2223ab2fdbdc59f9c", "status": "affected", "versionType": "git" }, { "version": "c7423dbdbc9ecef7fff5239d144cad4b9887f4de", "lessThan": "9a95c5bfbf02a0a7f5983280fe284a0ff0836c34", "status": "affected", "versionType": "git" }, { "version": "38d48fd224036717fcb3437e7af1314f6ebcd2d0", "status": "affected", "versionType": "git" }, { "version": "69c60b2a2dbb4887739d3a13297cc0dae3793f35", "status": "affected", "versionType": "git" }, { "version": "5.10.163", "lessThan": "5.10.222", "status": "affected", "versionType": "semver" }, { "version": "5.15.86", "lessThan": "5.15.163", "status": "affected", "versionType": "semver" }, { "version": "6.1.2", "lessThan": "6.1.98", "status": "affected", "versionType": "semver" }, { "version": "5.4.229", "lessThan": "5.5", "status": "affected", "versionType": "semver" }, { "version": "6.0.16", "lessThan": "6.1", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/linux/lsm_hook_defs.h", "include/linux/security.h", "kernel/auditfilter.c", "security/apparmor/audit.c", "security/apparmor/include/audit.h", "security/integrity/ima/ima.h", "security/integrity/ima/ima_policy.c", "security/security.c", "security/selinux/include/audit.h", "security/selinux/ss/services.c", "security/smack/smack_lsm.c" ], "versions": [ { "version": "6.2", "status": "affected" }, { "version": "0", "lessThan": "6.2", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.222", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.163", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.98", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.39", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.9.7", "lessThanOrEqual": "6.9.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.10", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.10.163", "versionEndExcluding": "5.10.222" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15.86", "versionEndExcluding": "5.15.163" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1.2", "versionEndExcluding": "6.1.98" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.39" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.9.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4.229" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.0.16" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/a6176a802c4bfb83bf7524591aa75f44a639a853" }, { "url": "https://git.kernel.org/stable/c/a38e02265c681b51997a264aaf743095e2ee400a" }, { "url": "https://git.kernel.org/stable/c/9c3906c3738562b1fedc6f1cfc81756a7cfefff0" }, { "url": "https://git.kernel.org/stable/c/28d0ecc52f6c927d0e9ba70a4f2c1ea15453ee88" }, { "url": "https://git.kernel.org/stable/c/58275455893066149e9f4df2223ab2fdbdc59f9c" }, { "url": "https://git.kernel.org/stable/c/9a95c5bfbf02a0a7f5983280fe284a0ff0836c34" } ], "title": "ima: Avoid blocking in RCU read-side critical section", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/a6176a802c4bfb83bf7524591aa75f44a639a853", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/a38e02265c681b51997a264aaf743095e2ee400a", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/9c3906c3738562b1fedc6f1cfc81756a7cfefff0", "tags": [ "x_transferred" ] }, { "url": 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