Messages in this thread | | | From | Sam Sun <> | Date | Wed, 17 Apr 2024 21:37:47 +0800 | Subject | [Linux kernel bug] WARNING in free_event |
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Dear developers and maintainers,
We encountered a kernel warning in the function free_event() while using our modified syzkaller. It was tested on the latest upstream linux(6.9-rc4). C repro and kernel config are attached to this email. Kernel dump log is listed below. ```
------------[ cut here ]------------ unexpected event refcount: 2; ptr=ffff88801931e0c0 WARNING: CPU: 0 PID: 8082 at kernel/events/core.c:5254 free_event+0xa3/0xc0 kernel/events/core.c:5254 Modules linked in: CPU: 0 PID: 8082 Comm: syz-executor381 Not tainted 6.7.0-rc7 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 RIP: 0010:free_event+0xa3/0xc0 kernel/events/core.c:5254 Code: b8 00 00 00 00 00 fc ff df 48 c1 ea 03 80 3c 02 00 75 25 48 8b b5 38 02 00 00 48 89 ea 48 c7 c7 c0 38 b7 8a e8 6e 30 9e ff 90 <0f> 0b 90 90 5d 41 5c 41 5d e9 bf 45 d7 ff 4c 89 ef e8 d7 e9 2b 00 RSP: 0018:ffffc9000176f9e8 EFLAGS: 00010282 RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffffffff814c00fa RDX: ffff888063d919c0 RSI: ffffffff814c0107 RDI: 0000000000000001 RBP: ffff88801931e0c0 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000002 R13: ffff88801931e2f8 R14: ffff88801931e3a0 R15: ffff88801931e0c0 FS: 0000000000000000(0000) GS:ffff888044200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020000008 CR3: 000000000cd78000 CR4: 0000000000750ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: <TASK> perf_event_release_kernel+0x5d4/0x8f0 kernel/events/core.c:5421 perf_release+0x37/0x50 kernel/events/core.c:5442 __fput+0x282/0xbb0 fs/file_table.c:394 task_work_run+0x168/0x260 kernel/task_work.c:180 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0xaf0/0x2a40 kernel/exit.c:869 do_group_exit+0xd4/0x2a0 kernel/exit.c:1018 get_signal+0x243c/0x2630 kernel/signal.c:2904 arch_do_signal_or_restart+0x81/0x7d0 arch/x86/kernel/signal.c:309 exit_to_user_mode_loop kernel/entry/common.c:168 [inline] exit_to_user_mode_prepare+0x121/0x240 kernel/entry/common.c:204 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline] syscall_exit_to_user_mode+0x1e/0x60 kernel/entry/common.c:296 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242 </TASK> ``` If you have any questions, please contact us. Reported by: Yue Sun <samsun1006219@gmail.com> Reported by: xingwei lee <xrivendell7@gmail.com>
Best Regards, Yue [unhandled content-type:application/octet-stream]#define _GNU_SOURCE
#include <dirent.h> #include <endian.h> #include <errno.h> #include <fcntl.h> #include <sched.h> #include <signal.h> #include <stdarg.h> #include <stdbool.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/prctl.h> #include <sys/stat.h> #include <sys/syscall.h> #include <sys/types.h> #include <sys/wait.h> #include <time.h> #include <unistd.h>
static void sleep_ms(uint64_t ms) { usleep(ms * 1000); }
static uint64_t current_time_ms(void) { struct timespec ts; if (clock_gettime(CLOCK_MONOTONIC, &ts)) exit(1); return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000; }
#define BITMASK(bf_off, bf_len) (((1ull << (bf_len)) - 1) << (bf_off)) #define STORE_BY_BITMASK(type, htobe, addr, val, bf_off, bf_len) \ *(type*)(addr) = \ htobe((htobe(*(type*)(addr)) & ~BITMASK((bf_off), (bf_len))) | \ (((type)(val) << (bf_off)) & BITMASK((bf_off), (bf_len))))
static bool write_file(const char* file, const char* what, ...) { char buf[1024]; va_list args; va_start(args, what); vsnprintf(buf, sizeof(buf), what, args); va_end(args); buf[sizeof(buf) - 1] = 0; int len = strlen(buf); int fd = open(file, O_WRONLY | O_CLOEXEC); if (fd == -1) return false; if (write(fd, buf, len) != len) { int err = errno; close(fd); errno = err; return false; } close(fd); return true; }
static void kill_and_wait(int pid, int* status) { kill(-pid, SIGKILL); kill(pid, SIGKILL); for (int i = 0; i < 100; i++) { if (waitpid(-1, status, WNOHANG | __WALL) == pid) return; usleep(1000); } DIR* dir = opendir("/sys/fs/fuse/connections"); if (dir) { for (;;) { struct dirent* ent = readdir(dir); if (!ent) break; if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0) continue; char abort[300]; snprintf(abort, sizeof(abort), "/sys/fs/fuse/connections/%s/abort", ent->d_name); int fd = open(abort, O_WRONLY); if (fd == -1) { continue; } if (write(fd, abort, 1) < 0) { } close(fd); } closedir(dir); } else { } while (waitpid(-1, status, __WALL) != pid) { } }
static void setup_test() { prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0); setpgrp(); write_file("/proc/self/oom_score_adj", "1000"); }
#define USLEEP_FORKED_CHILD (3 * 50 * 1000)
static long handle_clone_ret(long ret) { if (ret != 0) { return ret; } usleep(USLEEP_FORKED_CHILD); syscall(__NR_exit, 0); while (1) { } }
static long syz_clone(volatile long flags, volatile long stack, volatile long stack_len, volatile long ptid, volatile long ctid, volatile long tls) { long sp = (stack + stack_len) & ~15; long ret = (long)syscall(__NR_clone, flags & ~CLONE_VM, sp, ptid, ctid, tls); return handle_clone_ret(ret); }
static void execute_one(void);
#define WAIT_FLAGS __WALL
static void loop(void) { int iter = 0; for (;; iter++) { int pid = fork(); if (pid < 0) exit(1); if (pid == 0) { setup_test(); execute_one(); exit(0); } int status = 0; uint64_t start = current_time_ms(); for (;;) { if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid) break; sleep_ms(1); if (current_time_ms() - start < 5000) continue; kill_and_wait(pid, &status); break; } } }
void execute_one(void) { *(uint32_t*)0x20000000 = 0; *(uint32_t*)0x20000004 = 0x80; *(uint8_t*)0x20000008 = 0; *(uint8_t*)0x20000009 = 0; *(uint8_t*)0x2000000a = 0; *(uint8_t*)0x2000000b = 0; *(uint32_t*)0x2000000c = 0; *(uint64_t*)0x20000010 = 0x40000; *(uint64_t*)0x20000018 = 0; *(uint64_t*)0x20000020 = 0; STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 0, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 1, 1, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 2, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 3, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 4, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 5, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 6, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 7, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 8, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 9, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 10, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 11, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 12, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 13, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 14, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 15, 2); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 17, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 18, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 19, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 20, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 21, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 22, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 23, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 24, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 25, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 26, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 27, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 28, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 29, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 30, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 31, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 32, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 33, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 34, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 35, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 1, 36, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 1, 37, 1); STORE_BY_BITMASK(uint64_t, , 0x20000028, 0, 38, 26); *(uint32_t*)0x20000030 = 0; *(uint32_t*)0x20000034 = 0; *(uint64_t*)0x20000038 = 0x100000000000000; *(uint64_t*)0x20000040 = 0; *(uint64_t*)0x20000048 = 0; *(uint64_t*)0x20000050 = 0; *(uint32_t*)0x20000058 = 0; *(uint32_t*)0x2000005c = 0; *(uint64_t*)0x20000060 = 0; *(uint32_t*)0x20000068 = 0; *(uint16_t*)0x2000006c = 0; *(uint16_t*)0x2000006e = 0; *(uint32_t*)0x20000070 = 0; *(uint32_t*)0x20000074 = 0; *(uint64_t*)0x20000078 = 0; syscall(__NR_perf_event_open, /*attr=*/0x20000000ul, /*pid=*/0, /*cpu=*/0ul, /*group=*/-1, /*flags=*/0ul); syz_clone(/*flags=*/0, /*stack=*/0, /*stack_len=*/0, /*parentid=*/0, /*childtid=*/0, /*tls=*/0); } int main(void) { syscall(__NR_mmap, /*addr=*/0x1ffff000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1, /*offset=*/0ul); syscall(__NR_mmap, /*addr=*/0x20000000ul, /*len=*/0x1000000ul, /*prot=PROT_WRITE|PROT_READ|PROT_EXEC*/ 7ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1, /*offset=*/0ul); syscall(__NR_mmap, /*addr=*/0x21000000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1, /*offset=*/0ul); loop(); return 0; }
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