kernel/module.c: compare symbol values when marking symbols as exported in /proc/kallsyms. (ca4787b7) · Commits · 戴 / test

When there are two symbols in a module with the same name, one of which is exported, both will be marked as exported in /proc/kallsyms. There aren't any instances of this in the current kernel, but it is easy to construct a simple module with two compilation units that exhibits the problem. $ objdump -j .text -t testmod.ko | grep foo 00000000 l F .text 00000032 foo 00000080 g F .text 00000001 foo $ sudo insmod testmod.ko $ grep "T foo" /proc/kallsyms c28e8000 T foo [testmod] c28e8080 T foo [testmod] Fix this by comparing the symbol values once we've found the exported symbol table entry matching the symbol name. Tested using Ksplice: $ ksplice-create --patch=this_commit.patch --id=bar . $ sudo ksplice-apply ksplice-bar.tar.gz Done! $ grep "T foo" /proc/kallsyms c28e8080 T foo [testmod] Signed-off-by:

Tim Abbott <tabbott@mit.edu> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Rusty Russell <rusty@rustcorp.com.au>

kernel/module.c

+8 −8

Original line number	Original line	Diff line number	Diff line
	@@ -1725,15 +1725,15 @@ static const struct kernel_symbol lookup_symbol(const char name,
	return NULL;		return NULL;
	}		}

	static int is_exported(const char name, const struct module mod)		static int is_exported(const char *name, unsigned long value,
			const struct module *mod)
	{		{
	if (!mod && lookup_symbol(name, __start___ksymtab, __stop___ksymtab))		const struct kernel_symbol *ks;
	return 1;		if (!mod)
	else		ks = lookup_symbol(name, __start___ksymtab, __stop___ksymtab);
	if (mod && lookup_symbol(name, mod->syms, mod->syms + mod->num_syms))
	return 1;
	else		else
	return 0;		ks = lookup_symbol(name, mod->syms, mod->syms + mod->num_syms);
			return ks != NULL && ks->value == value;
	}		}

	/* As per nm */		/* As per nm */
	@@ -2504,7 +2504,7 @@ int module_get_kallsym(unsigned int symnum, unsigned long value, char type,
	strlcpy(name, mod->strtab + mod->symtab[symnum].st_name,		strlcpy(name, mod->strtab + mod->symtab[symnum].st_name,
	KSYM_NAME_LEN);		KSYM_NAME_LEN);
	strlcpy(module_name, mod->name, MODULE_NAME_LEN);		strlcpy(module_name, mod->name, MODULE_NAME_LEN);
	*exported = is_exported(name, mod);		exported = is_exported(name, value, mod);
	preempt_enable();		preempt_enable();
	return 0;		return 0;
	}		}

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