kernel/module.c: compare symbol values when marking symbols as exported in /proc/kallsyms.
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>
diff --git a/kernel/module.c b/kernel/module.c
index dd2a541..895c567 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1725,15 +1725,15 @@
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))
- return 1;
+ const struct kernel_symbol *ks;
+ if (!mod)
+ ks = lookup_symbol(name, __start___ksymtab, __stop___ksymtab);
else
- if (mod && lookup_symbol(name, mod->syms, mod->syms + mod->num_syms))
- return 1;
- else
- return 0;
+ ks = lookup_symbol(name, mod->syms, mod->syms + mod->num_syms);
+ return ks != NULL && ks->value == value;
}
/* As per nm */
@@ -2504,7 +2504,7 @@
strlcpy(name, mod->strtab + mod->symtab[symnum].st_name,
KSYM_NAME_LEN);
strlcpy(module_name, mod->name, MODULE_NAME_LEN);
- *exported = is_exported(name, mod);
+ *exported = is_exported(name, *value, mod);
preempt_enable();
return 0;
}