KMSAN: uninit-value in sr_check_events
From: Dipanjan Das
Date: Sun Feb 12 2023 - 02:40:06 EST
Hi,
We would like to report the following bug which has been found by our
modified version of syzkaller.
======================================================
description: KMSAN: uninit-value in sr_check_events
affected file: drivers/scsi/sr.c
kernel version: 6.2.0-rc5
kernel commit: 41c66f47061608dc1fd493eebce198f0e74cc2d7
git tree: kmsan
kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=a9a22da1efde3af6
crash reproducer: attached
======================================================
Crash log:
======================================================
BUG: KMSAN: uninit-value in sr_check_events+0x12d2/0x13c0 drivers/scsi/sr.c:269
sr_check_events+0x12d2/0x13c0 drivers/scsi/sr.c:269
cdrom_update_events drivers/cdrom/cdrom.c:1485 [inline]
cdrom_check_events+0x61/0x170 drivers/cdrom/cdrom.c:1495
sr_block_check_events+0xf5/0x130 drivers/scsi/sr.c:559
disk_check_events+0xf1/0x950 block/disk-events.c:193
disk_clear_events block/disk-events.c:248 [inline]
bdev_check_media_change+0x26a/0x7f0 block/disk-events.c:279
sr_block_open+0x159/0x340 drivers/scsi/sr.c:494
blkdev_get_whole+0xb4/0x700 block/bdev.c:672
blkdev_get_by_dev+0x4c9/0x1280 block/bdev.c:822
blkdev_open+0x216/0x440 block/fops.c:478
do_dentry_open+0xf85/0x1970 fs/open.c:882
vfs_open+0x75/0xa0 fs/open.c:1013
do_open fs/namei.c:3557 [inline]
path_openat+0x4c4b/0x5a00 fs/namei.c:3714
do_filp_open+0x252/0x660 fs/namei.c:3741
do_sys_openat2+0x200/0x920 fs/open.c:1310
do_sys_open fs/open.c:1326 [inline]
__do_sys_openat fs/open.c:1342 [inline]
__se_sys_openat fs/open.c:1337 [inline]
__x64_sys_openat+0x285/0x310 fs/open.c:1337
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Uninit was stored to memory at:
sr_check_events+0xb04/0x13c0 drivers/scsi/sr.c:216
cdrom_update_events drivers/cdrom/cdrom.c:1485 [inline]
cdrom_check_events+0x61/0x170 drivers/cdrom/cdrom.c:1495
sr_block_check_events+0xf5/0x130 drivers/scsi/sr.c:559
disk_check_events+0xf1/0x950 block/disk-events.c:193
disk_clear_events block/disk-events.c:248 [inline]
bdev_check_media_change+0x26a/0x7f0 block/disk-events.c:279
sr_block_open+0x159/0x340 drivers/scsi/sr.c:494
blkdev_get_whole+0xb4/0x700 block/bdev.c:672
blkdev_get_by_dev+0x4c9/0x1280 block/bdev.c:822
blkdev_open+0x216/0x440 block/fops.c:478
do_dentry_open+0xf85/0x1970 fs/open.c:882
vfs_open+0x75/0xa0 fs/open.c:1013
do_open fs/namei.c:3557 [inline]
path_openat+0x4c4b/0x5a00 fs/namei.c:3714
do_filp_open+0x252/0x660 fs/namei.c:3741
do_sys_openat2+0x200/0x920 fs/open.c:1310
do_sys_open fs/open.c:1326 [inline]
__do_sys_openat fs/open.c:1342 [inline]
__se_sys_openat fs/open.c:1337 [inline]
__x64_sys_openat+0x285/0x310 fs/open.c:1337
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Local variable sshdr.i created at:
sr_get_events drivers/scsi/sr.c:172 [inline]
sr_check_events+0x11f/0x13c0 drivers/scsi/sr.c:215
cdrom_update_events drivers/cdrom/cdrom.c:1485 [inline]
cdrom_check_events+0x61/0x170 drivers/cdrom/cdrom.c:1495
CPU: 0 PID: 22994 Comm: syz-executor.1 Not tainted
6.2.0-rc5-00010-g41c66f470616 #8
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
--
Thanks and Regards,
Dipanjan
Attachment:
repro.syz
Description: Binary data
// autogenerated by syzkaller (https://github.com/google/syzkaller)
#define _GNU_SOURCE
#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.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;
}
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 int inject_fault(int nth)
{
int fd;
fd = open("/proc/thread-self/fail-nth", O_RDWR);
if (fd == -1)
exit(1);
char buf[16];
sprintf(buf, "%d", nth);
if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))
exit(1);
return fd;
}
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");
}
static void setup_fault()
{
static struct {
const char* file;
const char* val;
bool fatal;
} files[] = {
{"/sys/kernel/debug/failslab/ignore-gfp-wait", "N", true},
{"/sys/kernel/debug/fail_futex/ignore-private", "N", false},
{"/sys/kernel/debug/fail_page_alloc/ignore-gfp-highmem", "N", false},
{"/sys/kernel/debug/fail_page_alloc/ignore-gfp-wait", "N", false},
{"/sys/kernel/debug/fail_page_alloc/min-order", "0", false},
};
unsigned i;
for (i = 0; i < sizeof(files) / sizeof(files[0]); i++) {
if (!write_file(files[i].file, files[i].val)) {
if (files[i].fatal)
exit(1);
}
}
}
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)
{
memcpy((void*)0x20000040, "/dev/sr0\000", 9);
inject_fault(7);
syscall(__NR_openat, 0xffffffffffffff9cul, 0x20000040ul, 0x48800ul, 0ul);
}
int main(void)
{
syscall(__NR_mmap, 0x1ffff000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul);
syscall(__NR_mmap, 0x21000000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
setup_fault();
loop();
return 0;
}