Andreas Gruenbacher <[email protected]> wrote:
>
> Got a customer bug report (https://bugzilla.novell.com/190296)
> about kernel symbols longer than 127 characters which end up in
> a string buffer that is not NULL terminated, leading to garbage
> in /proc/kallsyms. Using strlcpy prevents this from happening,
> even though such symbols still won't come out right.
>
> A better fix would be to not use a fixed-size buffer, but it's
> probably not worth the trouble. (Modversion'ed symbols even have
> a length limit of 60.)
>
> (This patch has been ested on a 2.6.16 kernel.)
>
> Signed-off-by: Andreas Gruenbacher <[email protected]>
>
> Index: linux-2.6.17/kernel/module.c
> ===================================================================
> --- linux-2.6.17.orig/kernel/module.c
> +++ linux-2.6.17/kernel/module.c
> @@ -1935,7 +1935,7 @@ struct module *module_get_kallsym(unsign
> if (symnum < mod->num_symtab) {
> *value = mod->symtab[symnum].st_value;
> *type = mod->symtab[symnum].st_info;
> - strncpy(namebuf,
> + strlcpy(namebuf,
> mod->strtab + mod->symtab[symnum].st_name,
> 127);
> mutex_unlock(&module_mutex);
Yeah, that assume-the-caller-gave-us-a-128-byte-buffer is a bit rude. How
about this?
include/linux/module.h | 6 ++----
kernel/kallsyms.c | 4 ++--
kernel/module.c | 11 ++++-------
3 files changed, 8 insertions(+), 13 deletions(-)
diff -puN kernel/module.c~null-terminate-over-long-proc-kallsyms-symbols kernel/module.c
--- a/kernel/module.c~null-terminate-over-long-proc-kallsyms-symbols
+++ a/kernel/module.c
@@ -2019,10 +2019,8 @@ const char *module_address_lookup(unsign
return NULL;
}
-struct module *module_get_kallsym(unsigned int symnum,
- unsigned long *value,
- char *type,
- char namebuf[128])
+struct module *module_get_kallsym(unsigned int symnum, unsigned long *value,
+ char *type, char *name, size_t namelen)
{
struct module *mod;
@@ -2031,9 +2029,8 @@ struct module *module_get_kallsym(unsign
if (symnum < mod->num_symtab) {
*value = mod->symtab[symnum].st_value;
*type = mod->symtab[symnum].st_info;
- strncpy(namebuf,
- mod->strtab + mod->symtab[symnum].st_name,
- 127);
+ strlcpy(name, mod->strtab + mod->symtab[symnum].st_name,
+ namelen);
mutex_unlock(&module_mutex);
return mod;
}
diff -puN include/linux/module.h~null-terminate-over-long-proc-kallsyms-symbols include/linux/module.h
--- a/include/linux/module.h~null-terminate-over-long-proc-kallsyms-symbols
+++ a/include/linux/module.h
@@ -362,10 +362,8 @@ int is_module_address(unsigned long addr
/* Returns module and fills in value, defined and namebuf, or NULL if
symnum out of range. */
-struct module *module_get_kallsym(unsigned int symnum,
- unsigned long *value,
- char *type,
- char namebuf[128]);
+struct module *module_get_kallsym(unsigned int symnum, unsigned long *value,
+ char *type, char *name, size_t namelen);
/* Look for this name: can be of form module:name. */
unsigned long module_kallsyms_lookup_name(const char *name);
diff -puN kernel/kallsyms.c~null-terminate-over-long-proc-kallsyms-symbols kernel/kallsyms.c
--- a/kernel/kallsyms.c~null-terminate-over-long-proc-kallsyms-symbols
+++ a/kernel/kallsyms.c
@@ -275,8 +275,8 @@ static void upcase_if_global(struct kall
static int get_ksymbol_mod(struct kallsym_iter *iter)
{
iter->owner = module_get_kallsym(iter->pos - kallsyms_num_syms,
- &iter->value,
- &iter->type, iter->name);
+ &iter->value, &iter->type,
+ iter->name, sizeof(iter->name));
if (iter->owner == NULL)
return 0;
_
-
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