[PATCH v2 1/2] module/kallsyms: fix nextval for data symbol lookup

[Stanislaw Gruszka <stf_xl@wp.pl>]

The symbol lookup code assumes the queried address resides in either
MOD_TEXT or MOD_INIT_TEXT. This breaks for addresses in other module
memory regions (e.g. rodata or data), resulting in incorrect upper
bounds and wrong symbol size.

Select the module memory region the address belongs to instead of
hardcoding text sections. Also initialize the lower bound to the start
of that region, as searching from address 0 is unnecessary.

Signed-off-by: Stanislaw Gruszka <stf_xl@wp.pl>
---
v1 -> v2: new patch.

 kernel/module/kallsyms.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index 0fc11e45df9b..f23126d804b2 100644
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c
@@ -258,17 +258,25 @@ static const char *find_kallsyms_symbol(struct module *mod,
 	unsigned int i, best = 0;
 	unsigned long nextval, bestval;
 	struct mod_kallsyms *kallsyms = rcu_dereference(mod->kallsyms);
-	struct module_memory *mod_mem;
+	struct module_memory *mod_mem = NULL;
 
-	/* At worse, next value is at end of module */
-	if (within_module_init(addr, mod))
-		mod_mem = &mod->mem[MOD_INIT_TEXT];
-	else
-		mod_mem = &mod->mem[MOD_TEXT];
+	for_each_mod_mem_type(type) {
+#ifndef CONFIG_KALLSYMS_ALL
+		if (!mod_mem_type_is_text(type))
+			continue;
+#endif
+		if (within_module_mem_type(addr, mod, type)) {
+			mod_mem = &mod->mem[type];
+			break;
+		}
+	}
 
-	nextval = (unsigned long)mod_mem->base + mod_mem->size;
+	if (!mod_mem)
+		return NULL;
 
-	bestval = kallsyms_symbol_value(&kallsyms->symtab[best]);
+	/* Initialize bounds within memory region the address belongs to. */
+	nextval = (unsigned long)mod_mem->base + mod_mem->size;
+	bestval = (unsigned long)mod_mem->base - 1;
 
 	/*
 	 * Scan for closest preceding symbol, and next symbol. (ELF
-- 
2.50.1