{"id":"CVE-2024-40947","summary":"ima: Avoid blocking in RCU read-side critical section","details":"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 \u003c44\u003e 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==\u003e synchronize_rcu returns early\n|  kfree(entry)\t\t|\t\t\t|\n|\t\t\t|    entry = entry-\u003enext|\n==\u003e UAF happens and entry now becomes NULL (or could be anything).\n|\t\t\t|    entry-\u003eaction\t|\n==\u003e 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]","modified":"2026-04-16T04:34:36.428366745Z","published":"2024-07-12T12:31:52.810Z","related":["SUSE-SU-2024:2802-1","SUSE-SU-2024:2896-1","SUSE-SU-2024:2973-1","SUSE-SU-2025:20008-1","SUSE-SU-2025:20028-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/40xxx/CVE-2024-40947.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/28d0ecc52f6c927d0e9ba70a4f2c1ea15453ee88"},{"type":"WEB","url":"https://git.kernel.org/stable/c/58275455893066149e9f4df2223ab2fdbdc59f9c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9a95c5bfbf02a0a7f5983280fe284a0ff0836c34"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9c3906c3738562b1fedc6f1cfc81756a7cfefff0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a38e02265c681b51997a264aaf743095e2ee400a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a6176a802c4bfb83bf7524591aa75f44a639a853"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/40xxx/CVE-2024-40947.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-40947"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"c4b035b1f036ddd53fbfced49046e586c5ad8a3e"},{"fixed":"a6176a802c4bfb83bf7524591aa75f44a639a853"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"2d4bc60693c4206c64723e94ae5f7a04c0b8f18f"},{"fixed":"a38e02265c681b51997a264aaf743095e2ee400a"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"8008f1691c15f353f5a53dc5d450b8262cb57421"},{"fixed":"9c3906c3738562b1fedc6f1cfc81756a7cfefff0"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"c7423dbdbc9ecef7fff5239d144cad4b9887f4de"},{"fixed":"28d0ecc52f6c927d0e9ba70a4f2c1ea15453ee88"},{"fixed":"58275455893066149e9f4df2223ab2fdbdc59f9c"},{"fixed":"9a95c5bfbf02a0a7f5983280fe284a0ff0836c34"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0"},{"last_affected":"38d48fd224036717fcb3437e7af1314f6ebcd2d0"},{"last_affected":"69c60b2a2dbb4887739d3a13297cc0dae3793f35"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-40947.json"}}],"schema_version":"1.7.5"}