Hello,
The following program triggers WARNING in ioremap_wc:
------------[ cut here ]------------ LoadPin: kernel-module denied obj="/memfd: (deleted)" pid=12061 cmdline="/tmp/syz-executor" WARNING: CPU: 1 PID: 12056 at arch/x86/mm/ioremap.c:121[< none
] __ioremap_caller+0x348/0x6b0 arch/x86/mm/ioremap.c:120
LoadPin: kernel-module denied obj="/memfd: (deleted)" pid=12063 cmdline="/tmp/syz-executor" ioremap on RAM at 0x0000000020068000 - 0x0000000020068fff Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 12056 Comm: syz-executor Not tainted 4.8.0-rc3+ #32 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 ffffffff884b8280 ffff8800295777f0 ffffffff82d1b239 ffffffff00bd6000 fffffbfff1097050 ffffffff86e8eec0 ffff8800295778c8 ffffffff86e7ad00 dffffc0000000000 0000000000000009 ffff8800295778b8 ffffffff816ab4e3 Call Trace: [< inline >] __dump_stack lib/dump_stack.c:15 [<ffffffff82d1b239>] dump_stack+0x12e/0x185 lib/dump_stack.c:51 [<ffffffff816ab4e3>] panic+0x1e4/0x3ef kernel/panic.c:153 [<ffffffff813808f4>] __warn+0x1c4/0x1e0 kernel/panic.c:509 [<ffffffff813809bc>] warn_slowpath_fmt+0xac/0xd0 kernel/panic.c:532 [<ffffffff8129a1c8>] __ioremap_caller+0x348/0x6b0 arch/x86/mm/ioremap.c:120 [<ffffffff8129a5b6>] ioremap_wc+0x26/0x30 arch/x86/mm/ioremap.c:290 [<ffffffff833ff70e>] drm_addmap_core+0xf1e/0x16c0 drivers/gpu/drm/drm_bufs.c:213 [<ffffffff8340327a>] drm_legacy_addmap_ioctl+0x1ca/0x340 drivers/gpu/drm/drm_bufs.c:403 [<ffffffff83410a5c>] drm_ioctl+0x7bc/0xc60 drivers/gpu/drm/drm_ioctl.c:724 [< inline >] vfs_ioctl fs/ioctl.c:43 [<ffffffff8186f1fc>] do_vfs_ioctl+0x18c/0x1080 fs/ioctl.c:675 [< inline >] SYSC_ioctl fs/ioctl.c:690 [<ffffffff8187017f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:681 [<ffffffff810088ff>] do_syscall_64+0x1df/0x640 arch/x86/entry/common.c:288 [<ffffffff86c25543>] entry_SYSCALL64_slow_path+0x25/0x25 arch/x86/entry/entry_64.S:248
On commit 61c04572de404e52a655a36752e696bbcb483cf5 (Aug 25).
// autogenerated by syzkaller (http://github.com/google/syzkaller) #ifndef __NR_syz_open_pts #define __NR_syz_open_pts 1000002 #endif #ifndef __NR_mmap #define __NR_mmap 9 #endif #ifndef __NR_syz_open_dev #define __NR_syz_open_dev 1000001 #endif #ifndef __NR_ioctl #define __NR_ioctl 16 #endif #ifndef __NR_syz_fuse_mount #define __NR_syz_fuse_mount 1000003 #endif #ifndef __NR_syz_fuseblk_mount #define __NR_syz_fuseblk_mount 1000004 #endif
#include <fcntl.h> #include <pthread.h> #include <setjmp.h> #include <signal.h> #include <stddef.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/ioctl.h> #include <sys/stat.h> #include <sys/syscall.h> #include <sys/types.h> #include <unistd.h>
__thread int skip_segv; __thread jmp_buf segv_env;
static void segv_handler(int sig, siginfo_t* info, void* uctx) { if (__atomic_load_n(&skip_segv, __ATOMIC_RELAXED)) _longjmp(segv_env, 1); exit(sig); }
static void install_segv_handler() { struct sigaction sa; memset(&sa, 0, sizeof(sa)); sa.sa_sigaction = segv_handler; sa.sa_flags = SA_NODEFER | SA_SIGINFO; sigaction(SIGSEGV, &sa, NULL); sigaction(SIGBUS, &sa, NULL); }
#define NONFAILING(...) \ { \ __atomic_fetch_add(&skip_segv, 1, __ATOMIC_SEQ_CST); \ if (_setjmp(segv_env) == 0) { \ __VA_ARGS__; \ } \ __atomic_fetch_sub(&skip_segv, 1, __ATOMIC_SEQ_CST); \ }
static uintptr_t syz_open_dev(uintptr_t a0, uintptr_t a1, uintptr_t a2) { if (a0 == 0xc || a0 == 0xb) { char buf[128]; sprintf(buf, "/dev/%s/%d:%d", a0 == 0xc ? "char" : "block", (uint8_t)a1, (uint8_t)a2); return open(buf, O_RDWR, 0); } else { char buf[1024]; char* hash; strncpy(buf, (char*)a0, sizeof(buf)); buf[sizeof(buf) - 1] = 0; while ((hash = strchr(buf, '#'))) { *hash = '0' + (char)(a1 % 10); a1 /= 10; } return open(buf, a2, 0); } }
static uintptr_t syz_open_pts(uintptr_t a0, uintptr_t a1) { int ptyno = 0; if (ioctl(a0, TIOCGPTN, &ptyno)) return -1; char buf[128]; sprintf(buf, "/dev/pts/%d", ptyno); return open(buf, a1, 0); }
static uintptr_t syz_fuse_mount(uintptr_t a0, uintptr_t a1, uintptr_t a2, uintptr_t a3, uintptr_t a4, uintptr_t a5) { uint64_t target = a0; uint64_t mode = a1; uint64_t uid = a2; uint64_t gid = a3; uint64_t maxread = a4; uint64_t flags = a5;
int fd = open("/dev/fuse", O_RDWR); if (fd == -1) return fd; char buf[1024]; sprintf(buf, "fd=%d,user_id=%ld,group_id=%ld,rootmode=0%o", fd, (long)uid, (long)gid, (unsigned)mode & ~3u); if (maxread != 0) sprintf(buf + strlen(buf), ",max_read=%ld", (long)maxread); if (mode & 1) strcat(buf, ",default_permissions"); if (mode & 2) strcat(buf, ",allow_other"); syscall(SYS_mount, "", target, "fuse", flags, buf); return fd; }
static uintptr_t syz_fuseblk_mount(uintptr_t a0, uintptr_t a1, uintptr_t a2, uintptr_t a3, uintptr_t a4, uintptr_t a5, uintptr_t a6, uintptr_t a7) { uint64_t target = a0; uint64_t blkdev = a1; uint64_t mode = a2; uint64_t uid = a3; uint64_t gid = a4; uint64_t maxread = a5; uint64_t blksize = a6; uint64_t flags = a7;
int fd = open("/dev/fuse", O_RDWR); if (fd == -1) return fd; if (syscall(SYS_mknodat, AT_FDCWD, blkdev, S_IFBLK, makedev(7, 199))) return fd; char buf[256]; sprintf(buf, "fd=%d,user_id=%ld,group_id=%ld,rootmode=0%o", fd, (long)uid, (long)gid, (unsigned)mode & ~3u); if (maxread != 0) sprintf(buf + strlen(buf), ",max_read=%ld", (long)maxread); if (blksize != 0) sprintf(buf + strlen(buf), ",blksize=%ld", (long)blksize); if (mode & 1) strcat(buf, ",default_permissions"); if (mode & 2) strcat(buf, ",allow_other"); syscall(SYS_mount, blkdev, target, "fuseblk", flags, buf); return fd; }
static uintptr_t execute_syscall(int nr, uintptr_t a0, uintptr_t a1, uintptr_t a2, uintptr_t a3, uintptr_t a4, uintptr_t a5, uintptr_t a6, uintptr_t a7, uintptr_t a8) { switch (nr) { default: return syscall(nr, a0, a1, a2, a3, a4, a5); case __NR_syz_open_dev: return syz_open_dev(a0, a1, a2); case __NR_syz_open_pts: return syz_open_pts(a0, a1); case __NR_syz_fuse_mount: return syz_fuse_mount(a0, a1, a2, a3, a4, a5); case __NR_syz_fuseblk_mount: return syz_fuseblk_mount(a0, a1, a2, a3, a4, a5, a6, a7); } }
long r[10];
int main() { install_segv_handler(); memset(r, -1, sizeof(r)); r[0] = execute_syscall(__NR_mmap, 0x20000000ul, 0x85a000ul, 0x3ul, 0x32ul, 0xfffffffffffffffful, 0x0ul, 0, 0, 0); NONFAILING(memcpy( (void*)0x20000000, "\x2f\x64\x65\x76\x2f\x64\x72\x69\x2f\x63\x61\x72\x64\x23\x00", 15)); r[2] = execute_syscall(__NR_syz_open_dev, 0x20000000ul, 0x0ul, 0x400ul, 0, 0, 0, 0, 0, 0); NONFAILING(*(uint64_t*)0x20858fd8 = (uint64_t)0x20068000); NONFAILING(*(uint64_t*)0x20858fe0 = (uint64_t)0x1000); NONFAILING(*(uint32_t*)0x20858fe8 = (uint32_t)0x1); NONFAILING(*(uint32_t*)0x20858fec = (uint32_t)0x30); NONFAILING(*(uint64_t*)0x20858ff0 = (uint64_t)0x20284000); NONFAILING(*(uint32_t*)0x20858ff8 = (uint32_t)0x1); r[9] = execute_syscall(__NR_ioctl, r[2], 0xc0286415ul, 0x20858fd8ul, 0, 0, 0, 0, 0, 0); return 0; }