kallsyms: make KSYM_NAME_LEN include space for trailing '\0'

KSYM_NAME_LEN is peculiar in that it does not include the space for the
trailing '\0', forcing all users to use KSYM_NAME_LEN + 1 when allocating
buffer.  This is nonsense and error-prone.  Moreover, when the caller
forgets that it's very likely to subtly bite back by corrupting the stack
because the last position of the buffer is always cleared to zero.

This patch increments KSYM_NAME_LEN by one and updates code accordingly.

* off-by-one bug in asm-powerpc/kprobes.h::kprobe_lookup_name() macro
  is fixed.

* Where MODULE_NAME_LEN and KSYM_NAME_LEN were used together,
  MODULE_NAME_LEN was treated as if it didn't include space for the
  trailing '\0'.  Fix it.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Acked-by: Paulo Marques <pmarques@grupopie.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 5 deletions

diff --git a/kernel/module.c b/kernel/module.c
index 539fed9ac83c..33c04ad51175 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2133,7 +2133,7 @@ int lookup_module_symbol_name(unsigned long addr, char *symname)
                         sym = get_ksymbol(mod, addr, NULL, NULL);
                         if (!sym)
                                 goto out;
-                        strlcpy(symname, sym, KSYM_NAME_LEN + 1);
+                        strlcpy(symname, sym, KSYM_NAME_LEN);
                         mutex_unlock(&module_mutex);
                         return 0;
                 }
@@ -2158,9 +2158,9 @@ int lookup_module_symbol_attrs(unsigned long addr, unsigned long *size,
                         if (!sym)
                                 goto out;
                         if (modname)
-                                strlcpy(modname, mod->name, MODULE_NAME_LEN + 1);
+                                strlcpy(modname, mod->name, MODULE_NAME_LEN);
                         if (name)
-                                strlcpy(name, sym, KSYM_NAME_LEN + 1);
+                                strlcpy(name, sym, KSYM_NAME_LEN);
                         mutex_unlock(&module_mutex);
                         return 0;
                 }
@@ -2181,8 +2181,8 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
                         *value = mod->symtab[symnum].st_value;
                         *type = mod->symtab[symnum].st_info;
                         strlcpy(name, mod->strtab + mod->symtab[symnum].st_name,
-                                KSYM_NAME_LEN + 1);
-                        strlcpy(module_name, mod->name, MODULE_NAME_LEN + 1);
+                                KSYM_NAME_LEN);
+                        strlcpy(module_name, mod->name, MODULE_NAME_LEN);
                         *exported = is_exported(name, mod);
                         mutex_unlock(&module_mutex);
                         return 0;