The list of loaded modules is walked through in module_kallsyms_on_each_symbol (called by kallsyms_on_each_symbol). The module_mutex lock should be acquired to prevent potential corruptions in the list. This was uncovered with new lockdep asserts in module code introduced by the commit 0be964be0d45 ("module: Sanitize RCU usage and locking") in recent next- trees.
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| @@ -179,7 +179,9 @@ static int klp_find_object_symbol(const char *objname, const char *name, · 178 unmodified lines | ||
| 179 | 179 | .count = 0 |
| 180 | 180 | }; |
| 181 | 181 | |
| 182 | + mutex_lock(&module_mutex); | |
| 182 | 183 | kallsyms_on_each_symbol(klp_find_callback, &args); |
| 184 | + mutex_unlock(&module_mutex); | |
| 183 | 185 | |
| 184 | 186 | if (args.count == 0) |
| 185 | 187 | pr_err("symbol '%s' not found in symbol table\n", name); |
| @@ -219,13 +221,19 @@ static int klp_verify_vmlinux_symbol(const char *name, unsigned long addr) · 33 unmodified lines | ||
| 219 | 221 | .name = name, |
| 220 | 222 | .addr = addr, |
| 221 | 223 | }; |
| 224 | + int ret; | |
| 222 | 225 | |
| 223 | − if (kallsyms_on_each_symbol(klp_verify_callback, &args)) | |
| 224 | − return 0; | |
| 226 | + mutex_lock(&module_mutex); | |
| 227 | + ret = kallsyms_on_each_symbol(klp_verify_callback, &args); | |
| 228 | + mutex_unlock(&module_mutex); | |
| 225 | 229 | |
| 226 | − pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?\n", | |
| 227 | − name, addr); | |
| 228 | − return -EINVAL; | |
| 230 | + if (!ret) { | |
| 231 | + pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?\n", | |
| 232 | + name, addr); | |
| 233 | + return -EINVAL; | |
| 234 | + } | |
| 235 | + | |
| 236 | + return 0; | |
| 229 | 237 | } |
| 230 | 238 | |
| 231 | 239 | static int klp_find_verify_func_addr(struct klp_object *obj, |