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    SubjectRe: [PATCH v2] kernel: kallsyms: memory override issue, need check destination buffer length
    On 2013年04月15日 10:05, Rusty Russell wrote:
    > 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>’
    >

    oh... it is my fault, I will send v3.

    I only tested kallsyms_on_each_symbol and kallsyms_lookup_name (they
    were of cause OK). , not test others.

    ARRAY_SIZE is really valuable to help find bugs.

    and next, after code changes, I should compile it again, at least.

    :-)


    > Cheers,


    --
    Chen Gang

    Asianux Corporation
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