ghsa-mcj2-pgr8-h65p
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
ima: Avoid blocking in RCU read-side critical section
A panic happens in ima_match_policy:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000010 PGD 42f873067 P4D 0 Oops: 0000 [#1] SMP NOPTI CPU: 5 PID: 1286325 Comm: kubeletmonit.sh Kdump: loaded Tainted: P Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015 RIP: 0010:ima_match_policy+0x84/0x450 Code: 49 89 fc 41 89 cf 31 ed 89 44 24 14 eb 1c 44 39 7b 18 74 26 41 83 ff 05 74 20 48 8b 1b 48 3b 1d f2 b9 f4 00 0f 84 9c 01 00 00 <44> 85 73 10 74 ea 44 8b 6b 14 41 f6 c5 01 75 d4 41 f6 c5 02 74 0f RSP: 0018:ff71570009e07a80 EFLAGS: 00010207 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000200 RDX: ffffffffad8dc7c0 RSI: 0000000024924925 RDI: ff3e27850dea2000 RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffffabfce739 R10: ff3e27810cc42400 R11: 0000000000000000 R12: ff3e2781825ef970 R13: 00000000ff3e2785 R14: 000000000000000c R15: 0000000000000001 FS: 00007f5195b51740(0000) GS:ff3e278b12d40000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000010 CR3: 0000000626d24002 CR4: 0000000000361ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ima_get_action+0x22/0x30 process_measurement+0xb0/0x830 ? page_add_file_rmap+0x15/0x170 ? alloc_set_pte+0x269/0x4c0 ? prep_new_page+0x81/0x140 ? simple_xattr_get+0x75/0xa0 ? selinux_file_open+0x9d/0xf0 ima_file_check+0x64/0x90 path_openat+0x571/0x1720 do_filp_open+0x9b/0x110 ? page_counter_try_charge+0x57/0xc0 ? files_cgroup_alloc_fd+0x38/0x60 ? __alloc_fd+0xd4/0x250 ? do_sys_open+0x1bd/0x250 do_sys_open+0x1bd/0x250 do_syscall_64+0x5d/0x1d0 entry_SYSCALL_64_after_hwframe+0x65/0xca
Commit c7423dbdbc9e ("ima: Handle -ESTALE returned by ima_filter_rule_match()") introduced call to ima_lsm_copy_rule within a RCU read-side critical section which contains kmalloc with GFP_KERNEL. This implies a possible sleep and violates limitations of RCU read-side critical sections on non-PREEMPT systems.
Sleeping within RCU read-side critical section might cause synchronize_rcu() returning early and break RCU protection, allowing a UAF to happen.
The root cause of this issue could be described as follows: | Thread A | Thread B | | |ima_match_policy | | | rcu_read_lock | |ima_lsm_update_rule | | | synchronize_rcu | | | | kmalloc(GFP_KERNEL)| | | sleep | ==> synchronize_rcu returns early | kfree(entry) | | | | entry = entry->next| ==> UAF happens and entry now becomes NULL (or could be anything). | | entry->action | ==> Accessing entry might cause panic.
To fix this issue, we are converting all kmalloc that is called within RCU read-side critical section to use GFP_ATOMIC.
[PM: fixed missing comment, long lines, !CONFIG_IMA_LSM_RULES case]
{
"affected": [],
"aliases": [
"CVE-2024-40947"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-07-12T13:15:17Z",
"severity": null
},
"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]",
"id": "GHSA-mcj2-pgr8-h65p",
"modified": "2024-07-18T12:30:51Z",
"published": "2024-07-12T15:31:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-40947"
},
{
"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"
}
],
"schema_version": "1.4.0",
"severity": []
}
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