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

[Rusty Russell]

Chen Gang <gang.chen@xxxxxxxxxxx> 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 âkallsyms_lookupâ:
kernel/kallsyms.c:305:78: error: negative width in bit-field â<anonymous>â
kernel/kallsyms.c: In function âlookup_symbol_nameâ:
kernel/kallsyms.c:327:78: error: negative width in bit-field â<anonymous>â
kernel/kallsyms.c: In function âlookup_symbol_attrsâ:
kernel/kallsyms.c:346:69: error: negative width in bit-field â<anonymous>â

Cheers,
Rusty.
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