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SubjectRe: [PATCH v4 3/7] kprobes: validate the symbol name provided during probe registration
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a nit or two, below...

On 04/21/2017 07:32 AM, Naveen N. Rao wrote:
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 6a128f3a7ed1..ff9b1ac72a38 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -1383,6 +1383,34 @@ bool within_kprobe_blacklist(unsigned long addr)
> }
>
> /*
> + * We mainly want to ensure that the provided string is of a reasonable length
> + * and is of the form [<mod_name>:]<sym_name>, so that this is safe to process
> + * further.
> + * We don't worry about invalid characters as those will just prevent
> + * matching existing kallsyms.
> + */
> +bool is_valid_kprobe_symbol_name(const char *name)
> +{
> + size_t sym_len;
> + const char *s;
> +
> + s = strnchr(name, ':', MODULE_NAME_LEN + KSYM_NAME_LEN + 1);
> + if (s) {
> + sym_len = (size_t)(s - name);
> + if (sym_len <= 0 || sym_len >= MODULE_NAME_LEN)

"sym_len <= 0" looks odd here, since sym_len is likely unsigned and would never be less than zero, anyway.

> + return false;
> + s++;
> + } else
> + s = name;
> +
> + sym_len = strnlen(s, KSYM_NAME_LEN);
> + if (sym_len <= 0 || sym_len >= KSYM_NAME_LEN)

here, too.

> + return false;
> +
> + return true;
> +}

PC

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