On Thursday, March 18, 2021 at 9:40:21 PM UTC+5:30 syzbot wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: 0d7588ab riscv: process: Fix no prototype for arch_dup_tas.. > git tree: git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git fixes > console output: https://syzkaller.appspot.com/x/log.txt?x=12dde5aed00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=81c0b708b31626cc > dashboard link: https://syzkaller.appspot.com/bug?extid=11bf59db879676f59e52 > userspace arch: riscv64 > CC: [asml.s...@xxxxxxxxx ax...@xxxxxxxxx io-u...@xxxxxxxxxxxxxxx linux-...@xxxxxxxxxxxxxxx] > > Unfortunately, I don't have any reproducer for this issue yet. > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+11bf59...@xxxxxxxxxxxxxxxxxxxxxxxxx > > INFO: task iou-sqp-4867:4871 blocked for more than 430 seconds. > Not tainted 5.12.0-rc2-syzkaller-00467-g0d7588ab9ef9 #0 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > task:iou-sqp-4867 state:D stack: 0 pid: 4871 ppid: 4259 flags:0x00000004 > Call Trace: > [<ffffffe003bc3252>] context_switch kernel/sched/core.c:4324 [inline] > [<ffffffe003bc3252>] __schedule+0x478/0xdec kernel/sched/core.c:5075 > [<ffffffe003bc3c2a>] schedule+0x64/0x166 kernel/sched/core.c:5154 > [<ffffffe0004b80ee>] io_uring_cancel_sqpoll+0x1de/0x294 fs/io_uring.c:8858 > [<ffffffe0004c19cc>] io_sq_thread+0x548/0xe58 fs/io_uring.c:6750 > [<ffffffe000005570>] ret_from_exception+0x0/0x14 > > Showing all locks held in the system: > 3 locks held by kworker/u4:0/7: > 3 locks held by kworker/1:0/19: > 1 lock held by khungtaskd/1556: > #0: ffffffe00592b5e8 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x32/0x1fa kernel/locking/lockdep.c:6329 > 1 lock held by klogd/3947: > 2 locks held by getty/4142: > #0: ffffffe00f1aa098 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x48 drivers/tty/tty_ldsem.c:340 > #1: ffffffd010b6f2e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x9ac/0xb08 drivers/tty/n_tty.c:2178 > 2 locks held by kworker/0:1/4375: > > ============================================= > > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzk...@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. Attaching a C reproducer for this bug: #define _GNU_SOURCE #include <fcntl.h> #include <signal.h> #include <stdint.h> #include <stdlib.h> #include <string.h> #include <sys/mman.h> #include <sys/syscall.h> #include <sys/wait.h> #include <time.h> #include <unistd.h> 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 SIZEOF_IO_URING_SQE 64 #define SIZEOF_IO_URING_CQE 16 #define SQ_TAIL_OFFSET 64 #define SQ_RING_MASK_OFFSET 256 #define SQ_RING_ENTRIES_OFFSET 264 #define CQ_RING_ENTRIES_OFFSET 268 #define CQ_CQES_OFFSET 320 struct io_sqring_offsets { uint32_t head; uint32_t tail; uint32_t ring_mask; uint32_t ring_entries; uint32_t flags; uint32_t dropped; uint32_t array; uint32_t resv1; uint64_t resv2; }; struct io_cqring_offsets { uint32_t head; uint32_t tail; uint32_t ring_mask; uint32_t ring_entries; uint32_t overflow; uint32_t cqes; uint64_t resv[2]; }; struct io_uring_params { uint32_t sq_entries; uint32_t cq_entries; uint32_t flags; uint32_t sq_thread_cpu; uint32_t sq_thread_idle; uint32_t features; uint32_t resv[4]; struct io_sqring_offsets sq_off; struct io_cqring_offsets cq_off; }; #define IORING_OFF_SQ_RING 0 #define IORING_OFF_SQES 0x10000000ULL #define sys_io_uring_setup 425 static long syz_io_uring_setup(volatile long a0, volatile long a1, volatile long a2, volatile long a3, volatile long a4, volatile long a5) { uint32_t entries = (uint32_t)a0; struct io_uring_params* setup_params = (struct io_uring_params*)a1; void* vma1 = (void*)a2; void* vma2 = (void*)a3; void** ring_ptr_out = (void**)a4; void** sqes_ptr_out = (void**)a5; uint32_t fd_io_uring = syscall(sys_io_uring_setup, entries, setup_params); uint32_t sq_ring_sz = setup_params->sq_off.array + setup_params->sq_entries * sizeof(uint32_t); uint32_t cq_ring_sz = setup_params->cq_off.cqes + setup_params->cq_entries * SIZEOF_IO_URING_CQE; uint32_t ring_sz = sq_ring_sz > cq_ring_sz ? sq_ring_sz : cq_ring_sz; *ring_ptr_out = mmap(vma1, ring_sz, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE | MAP_FIXED, fd_io_uring, IORING_OFF_SQ_RING); uint32_t sqes_sz = setup_params->sq_entries * SIZEOF_IO_URING_SQE; *sqes_ptr_out = mmap(vma2, sqes_sz, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE | MAP_FIXED, fd_io_uring, IORING_OFF_SQES); return fd_io_uring; } static long syz_io_uring_submit(volatile long a0, volatile long a1, volatile long a2, volatile long a3) { char* ring_ptr = (char*)a0; char* sqes_ptr = (char*)a1; char* sqe = (char*)a2; uint32_t sqes_index = (uint32_t)a3; uint32_t sq_ring_entries = *(uint32_t*)(ring_ptr + SQ_RING_ENTRIES_OFFSET); uint32_t cq_ring_entries = *(uint32_t*)(ring_ptr + CQ_RING_ENTRIES_OFFSET); uint32_t sq_array_off = (CQ_CQES_OFFSET + cq_ring_entries * SIZEOF_IO_URING_CQE + 63) & ~63; if (sq_ring_entries) sqes_index %= sq_ring_entries; char* sqe_dest = sqes_ptr + sqes_index * SIZEOF_IO_URING_SQE; memcpy(sqe_dest, sqe, SIZEOF_IO_URING_SQE); uint32_t sq_ring_mask = *(uint32_t*)(ring_ptr + SQ_RING_MASK_OFFSET); uint32_t* sq_tail_ptr = (uint32_t*)(ring_ptr + SQ_TAIL_OFFSET); uint32_t sq_tail = *sq_tail_ptr & sq_ring_mask; uint32_t sq_tail_next = *sq_tail_ptr + 1; uint32_t* sq_array = (uint32_t*)(ring_ptr + sq_array_off); *(sq_array + sq_tail) = sqes_index; __atomic_store_n(sq_tail_ptr, sq_tail_next, __ATOMIC_RELEASE); return 0; } static void kill_and_wait(int pid, int* status) { kill(-pid, SIGKILL); kill(pid, SIGKILL); while (waitpid(-1, status, __WALL) != pid) { } } #define WAIT_FLAGS __WALL uint64_t r[3] = {0xffffffffffffffff, 0x0, 0x0}; void trigger_bug(void) { intptr_t res = 0; *(uint32_t*)0x20000204 = 0; *(uint32_t*)0x20000208 = 2; *(uint32_t*)0x2000020c = 0; *(uint32_t*)0x20000210 = 0; *(uint32_t*)0x20000218 = -1; memset((void*)0x2000021c, 0, 12); res = -1; res = syz_io_uring_setup(0x7987, 0x20000200, 0x20400000, 0x20ffd000, 0x200000c0, 0x200001c0); if (res != -1) { r[0] = res; r[1] = *(uint64_t*)0x200000c0; r[2] = *(uint64_t*)0x200001c0; } *(uint8_t*)0x20000180 = 0xb; *(uint8_t*)0x20000181 = 1; *(uint16_t*)0x20000182 = 0; *(uint32_t*)0x20000184 = 0; *(uint64_t*)0x20000188 = 4; *(uint64_t*)0x20000190 = 0x20000140; *(uint64_t*)0x20000140 = 0x77359400; *(uint64_t*)0x20000148 = 0; *(uint32_t*)0x20000198 = 1; *(uint32_t*)0x2000019c = 0; *(uint64_t*)0x200001a0 = 0; *(uint16_t*)0x200001a8 = 0; *(uint16_t*)0x200001aa = 0; memset((void*)0x200001ac, 0, 20); syz_io_uring_submit(r[1], r[2], 0x20000180, 1); *(uint32_t*)0x20000544 = 0; *(uint32_t*)0x20000548 = 0x36; *(uint32_t*)0x2000054c = 0; *(uint32_t*)0x20000550 = 0; *(uint32_t*)0x20000558 = r[0]; memset((void*)0x2000055c, 0, 12); syz_io_uring_setup(0x4bf1, 0x20000540, 0x20ffd000, 0x20ffc000, 0, 0); } int main(void) { syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul); int pid = fork(); if (pid < 0) exit(1); if (pid == 0) { trigger_bug(); exit(0); } int status = 0; uint64_t start = current_time_ms(); for (;;) { if (current_time_ms() - start < 1000) { continue; } kill_and_wait(pid, &status); break; } return 0; }
