tree: https://github.com/0day-ci/linux/commits/UPDATE-20200613-235004/Borislav-... head: 24611fae296234f2f3d5e95062d44390a482887b commit: 24611fae296234f2f3d5e95062d44390a482887b [1/1] x86/msr: Filter MSR writes config: x86_64-randconfig-c002-20200613 (attached as .config) compiler: gcc-9 (Debian 9.3.0-13) 9.3.0 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>, old ones prefixed by <<): arch/x86/kernel/msr.c: In function 'set_allow_writes': 281 | char *s = strstrip(val); | ^~~ In file included from include/linux/bitmap.h:9, from include/linux/cpumask.h:12, from arch/x86/include/asm/cpumask.h:5, from arch/x86/include/asm/msr.h:11, from arch/x86/include/asm/processor.h:22, from arch/x86/include/asm/cpufeature.h:5, from arch/x86/include/asm/thread_info.h:53, from include/linux/thread_info.h:38, from arch/x86/include/asm/preempt.h:7, from include/linux/preempt.h:78, from include/linux/spinlock.h:51, from include/linux/seqlock.h:36, from include/linux/time.h:6, from include/linux/stat.h:19, from include/linux/module.h:13, from arch/x86/kernel/msr.c:22: include/linux/string.h:76:49: note: expected 'char *' but argument is of type 'const char *' 76 | static inline __must_check char *strstrip(char *str) | ~~~~~~^~~ In file included from include/linux/compiler_types.h:59, from <command-line>: arch/x86/kernel/msr.c: In function 'filter_write': 200 | # define fallthrough __attribute__((__fallthrough__)) | ^~~~~~~~~~~~~ 86 | default: fallthrough; | ^~~~~~~~~~~ vim +281 arch/x86/kernel/msr.c 80 81 static int filter_write(u32 reg) 82 { 83 switch (allow_writes) { 84 case MSR_WRITES_ON: return 0; break; 85 case MSR_WRITES_OFF: return -EPERM; break; 87 } 88 89 if (reg == MSR_IA32_ENERGY_PERF_BIAS) 90 return 0; 91 92 pr_err_ratelimited("Write to unrecognized MSR 0x%x by %s\n" 93 "Please report to x86(a)kernel.org\n&quot;, 94 reg, current->comm); 95 96 return 0; 97 } 98 99 static ssize_t msr_write(struct file *file, const char __user *buf, 100 size_t count, loff_t *ppos) 101 { 102 const u32 __user *tmp = (const u32 __user *)buf; 103 u32 data[2]; 104 u32 reg = *ppos; 105 int cpu = iminor(file_inode(file)); 106 int err = 0; 107 ssize_t bytes = 0; 108 109 err = security_locked_down(LOCKDOWN_MSR); 110 if (err) 111 return err; 112 113 err = filter_write(reg); 114 if (err) 115 return err; 116 117 if (count % 8) 118 return -EINVAL; /* Invalid chunk size */ 119 120 for (; count; count -= 8) { 121 if (copy_from_user(&data, tmp, 8)) { 122 err = -EFAULT; 123 break; 124 } 125 126 add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK); 127 128 err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]); 129 if (err) 130 break; 131 132 tmp += 2; 133 bytes += 8; 134 } 135 136 return bytes ? bytes : err; 137 } 138 139 static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg) 140 { 141 u32 __user *uregs = (u32 __user *)arg; 142 u32 regs[8]; 143 int cpu = iminor(file_inode(file)); 144 int err; 145 146 switch (ioc) { 147 case X86_IOC_RDMSR_REGS: 148 if (!(file->f_mode & FMODE_READ)) { 149 err = -EBADF; 150 break; 151 } 152 if (copy_from_user(&regs, uregs, sizeof(regs))) { 153 err = -EFAULT; 154 break; 155 } 156 err = rdmsr_safe_regs_on_cpu(cpu, regs); 157 if (err) 158 break; 159 if (copy_to_user(uregs, &regs, sizeof(regs))) 160 err = -EFAULT; 161 break; 162 163 case X86_IOC_WRMSR_REGS: 164 if (!(file->f_mode & FMODE_WRITE)) { 165 err = -EBADF; 166 break; 167 } 168 if (copy_from_user(&regs, uregs, sizeof(regs))) { 169 err = -EFAULT; 170 break; 171 } 172 err = security_locked_down(LOCKDOWN_MSR); 173 if (err) 174 break; 175 err = wrmsr_safe_regs_on_cpu(cpu, regs); 176 if (err) 177 break; 178 if (copy_to_user(uregs, &regs, sizeof(regs))) 179 err = -EFAULT; 180 break; 181 182 default: 183 err = -ENOTTY; 184 break; 185 } 186 187 return err; 188 } 189 190 static int msr_open(struct inode *inode, struct file *file) 191 { 192 unsigned int cpu = iminor(file_inode(file)); 193 struct cpuinfo_x86 *c; 194 195 if (!capable(CAP_SYS_RAWIO)) 196 return -EPERM; 197 198 if (cpu >= nr_cpu_ids || !cpu_online(cpu)) 199 return -ENXIO; /* No such CPU */ 200 201 c = &cpu_data(cpu); 202 if (!cpu_has(c, X86_FEATURE_MSR)) 203 return -EIO; /* MSR not supported */ 204 205 return 0; 206 } 207 208 /* 209 * File operations we support 210 */ 211 static const struct file_operations msr_fops = { 212 .owner = THIS_MODULE, 213 .llseek = no_seek_end_llseek, 214 .read = msr_read, 215 .write = msr_write, 216 .open = msr_open, 217 .unlocked_ioctl = msr_ioctl, 218 .compat_ioctl = msr_ioctl, 219 }; 220 221 static int msr_device_create(unsigned int cpu) 222 { 223 struct device *dev; 224 225 dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu), NULL, 226 "msr%d", cpu); 227 return PTR_ERR_OR_ZERO(dev); 228 } 229 230 static int msr_device_destroy(unsigned int cpu) 231 { 232 device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu)); 233 return 0; 234 } 235 236 static char *msr_devnode(struct device *dev, umode_t *mode) 237 { 238 return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt)); 239 } 240 241 static int __init msr_init(void) 242 { 243 int err; 244 245 if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) { 246 pr_err("unable to get major %d for msr\n", MSR_MAJOR); 247 return -EBUSY; 248 } 249 msr_class = class_create(THIS_MODULE, "msr"); 250 if (IS_ERR(msr_class)) { 251 err = PTR_ERR(msr_class); 252 goto out_chrdev; 253 } 254 msr_class->devnode = msr_devnode; 255 256 err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/msr:online", 257 msr_device_create, msr_device_destroy); 258 if (err < 0) 259 goto out_class; 260 cpuhp_msr_state = err; 261 return 0; 262 263 out_class: 264 class_destroy(msr_class); 265 out_chrdev: 266 __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr"); 267 return err; 268 } 269 module_init(msr_init); 270 271 static void __exit msr_exit(void) 272 { 273 cpuhp_remove_state(cpuhp_msr_state); 274 class_destroy(msr_class); 275 __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr"); 276 } 277 module_exit(msr_exit) 278 279 static int set_allow_writes(const char *val, const struct kernel_param *cp) 280 { 282 283 if (!strcmp(s, "on")) 284 allow_writes = MSR_WRITES_ON; 285 else if (!strcmp(s, "off")) 286 allow_writes = MSR_WRITES_OFF; 287 else 288 allow_writes = MSR_WRITES_DEFAULT; 289 290 return 0; 291 } 292 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org