If the string was too long to fit in the user-supplied buffer, the sysctl layer would zero-terminate it by writing past the end of the buffer. Don't do that. Noticed by Yi Yang <yang.y.yi@gmail.com>
Unified · Split
| @@ -2201,14 +2201,12 @@ int sysctl_string(ctl_table *table, int __user *name, int nlen, · 2200 unmodified lines | |||
| 2201 | if (get_user(len, oldlenp)) | 2201 | if (get_user(len, oldlenp)) |
| 2202 | return -EFAULT; | 2202 | return -EFAULT; |
| 2203 | if (len) { | 2203 | if (len) { |
| 2204 | l = strlen(table->data); | 2204 | l = strlen(table->data)+1; |
| 2205 | if (len > l) len = l; | 2205 | if (len > l) len = l; |
| 2206 | if (len >= table->maxlen) | 2206 | if (len >= table->maxlen) |
| 2207 | len = table->maxlen; | 2207 | len = table->maxlen; |
| 2208 | if(copy_to_user(oldval, table->data, len)) | 2208 | if(copy_to_user(oldval, table->data, len)) |
| 2209 | return -EFAULT; | 2209 | return -EFAULT; |
| 2210 | if(put_user(0, ((char __user *) oldval) + len)) | ||
| 2211 | return -EFAULT; | ||
| 2212 | if(put_user(len, oldlenp)) | 2210 | if(put_user(len, oldlenp)) |
| 2213 | return -EFAULT; | 2211 | return -EFAULT; |
| 2214 | } | 2212 | } |