Chen Gang <gang.c...@asianux.com> writes:
> We don't export any symbols > 128 characters, but if we did then
> kallsyms_expand_symbol() would overflow the buffer handed to it.
> So we need check destination buffer length when copying.
>
> the related test:
> if we define an EXPORT function which name more than 128.
> will panic when call kallsyms_lookup_name by init_kprobes on booting.
> after check the length (provide this patch), it is ok.
>
> Implementaion:
> add additional destination buffer length parameter (maxlen)
> if uncompressed string is too long (>= maxlen), it will be truncated.
> not check the parameters whether valid, since it is a static function.
>
>
> Signed-off-by: Chen Gang <gang.c...@asianux.com>
> Signed-off-by: Rusty Russell <ru...@rustcorp.com.au>
??!!! I never signed this off! I've never seen it before!
Minor comments below:
> -static unsigned int kallsyms_expand_symbol(unsigned int off, char *result)
> +static unsigned int kallsyms_expand_symbol(unsigned int off,
> + char *result, int maxlen)
'size_t maxlen' would be more explicit.
> {
> int len, skipped_first = 0;
> const u8 *tptr, *data;
> + char *begin = result;
> /* Get the compressed symbol length from the first symbol byte. */
> data = &kallsyms_names[off];
> @@ -113,14 +116,16 @@ static unsigned int kallsyms_expand_symbol(unsigned int
> off, char *result)
> while (*tptr) {
> if (skipped_first) {
> - *result = *tptr;
> - result++;
> + *result++ = *tptr;
> + if (result - begin == maxlen - 1)
> + goto tail;
You could just decrement maxlen instead, and handle maxlen == 0 at the
same time:
if (maxlen <= 1)
goto tail;
*result = *tptr;
result++;
maxlen--;
> @@ -176,7 +181,7 @@ unsigned long kallsyms_lookup_name(const char *name)
> unsigned int off;
> for (i = 0, off = 0; i < kallsyms_num_syms; i++) {
> - off = kallsyms_expand_symbol(off, namebuf);
> + off = kallsyms_expand_symbol(off, namebuf, sizeof(namebuf));
> if (strcmp(namebuf, name) == 0)
> return kallsyms_addresses[i];
I prefer to use ARRAY_SIZE(namebuf) instead of sizeof(namebuf). That
way we break compile if the declaration is changed from an array to a
pointer one day.
Same for the others.
Thanks,
Rusty.
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