Re: [PATCH v2] kernel: kallsyms: memory override issue, need check destination buffer length

[Rusty Russell <rusty@rustcorp.com.au>]

Chen Gang <gang.chen@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.

Found a bug already:

kernel/kallsyms.c: In function ‘kallsyms_lookup’:
kernel/kallsyms.c:305:78: error: negative width in bit-field ‘<anonymous>’
kernel/kallsyms.c: In function ‘lookup_symbol_name’:
kernel/kallsyms.c:327:78: error: negative width in bit-field ‘<anonymous>’
kernel/kallsyms.c: In function ‘lookup_symbol_attrs’:
kernel/kallsyms.c:346:69: error: negative width in bit-field ‘<anonymous>’

Cheers,
Rusty.