[PATCH] module: make symbol_put_addr() work for all exportedsymbols

[Jiri Kosina]

symbol_put_addr() works only for exported function names (symbols present 
in text section). This for example means that

        symbol_put_addr(__symbol_get("any_exported_variable_name"))

triggers a BUG, which really seems wrong.

This patch introduces generic lookup_symbol_address(), which performs 
lookup on symbol tables of all modules according to the address, and makes 
symbol_put_addr() use this interface to find the module owner instead.

Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>

diff --git a/kernel/module.c b/kernel/module.c
index 5f80478..77ff23e 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -302,6 +302,64 @@ static unsigned long find_symbol(const char *name,
 	return -ENOENT;
 }

+/* Lookup module symbol by address */
+const static struct kernel_symbol *lookup_symbol_address(unsigned long addr,
+		struct module **owner)
+{
+	struct module *mod;
+	const struct kernel_symbol *s;
+	unsigned int i;
+
+	/* Core kernel first */
+	struct {
+		const struct kernel_symbol *s_start;
+		const struct kernel_symbol *s_end;
+	} kern_syms[] = {
+		{ __start___ksymtab, __stop___ksymtab },
+		{ __start___ksymtab_gpl, __stop___ksymtab_gpl },
+		{ __start___ksymtab_gpl_future, __stop___ksymtab_gpl_future },
+		{ __start___ksymtab_unused, __stop___ksymtab_unused },
+		{ __start___ksymtab_unused_gpl, __stop___ksymtab_unused_gpl },
+	};
+
+	for (i = 0; i < ARRAY_SIZE(kern_syms); i++) {
+		for (s = kern_syms[i].s_start; s < kern_syms[i].s_end; s++) {
+			if (s->value == addr) {
+				if (owner)
+					*owner = NULL;
+				return s;
+			}
+		}
+	}
+
+	/* Now try modules */
+	list_for_each_entry(mod, &modules, list) {
+		struct {
+			const struct kernel_symbol *sym;
+			unsigned int num;
+		} arr[] = {
+			{ mod->syms, mod->num_syms },
+			{ mod->gpl_syms, mod->num_gpl_syms },
+			{ mod->gpl_future_syms, mod->num_gpl_future_syms },
+			{ mod->unused_syms, mod->num_unused_syms },
+			{ mod->unused_gpl_syms, mod->num_unused_gpl_syms },
+		};
+
+		for (i = 0; i < ARRAY_SIZE(arr); i++) {
+			for (s = arr[i].sym; s < arr[i].sym + arr[i].num; s++) {
+				if (s->value == addr) {
+					if (owner)
+						*owner = mod;
+					return s;
+				}
+			}
+		}
+	}
+	return NULL;
+}
+
+
+
 /* Search for module by name: must hold module_mutex. */
 static struct module *find_module(const char *name)
 {
@@ -799,13 +857,12 @@ EXPORT_SYMBOL(__symbol_put);
 void symbol_put_addr(void *addr)
 {
 	struct module *modaddr;
-
-	if (core_kernel_text((unsigned long)addr))
-		return;
-
-	if (!(modaddr = module_text_address((unsigned long)addr)))
+
+	if (!lookup_symbol_address((unsigned long)addr, &modaddr))
 		BUG();
-	module_put(modaddr);
+
+	if(modaddr)
+		module_put(modaddr);
 }
 EXPORT_SYMBOL_GPL(symbol_put_addr);



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