Messages in this thread | | | Date | Wed, 13 May 2009 13:23:03 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] Fix Warnining in arch/x86/kernel/signal.c |
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Ingo Molnar wrote: >>>> >>>> if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) >>>> goto badframe; >>>> - if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1 >>>> - && __copy_from_user(&set.sig[1], &frame->extramask, >>>> - sizeof(frame->extramask)))) >>>> + >>>> + if ( (__copy_from_user(&set.sig[1], &frame->extramask, >>>> + sizeof(frame->extramask)) && _NSIG_WORDS > 1) || >>>> + __get_user(set.sig[0], &frame->sc.oldmask)) >>>> goto badframe; >>> I'm not sure why this eliminates that warning. >>> set.sig[0] may not be initialized too, if __copy_from_user() failed. >> True, but only when either or both of __copy_from_user() and >> (_NSIG_WORDS > 1) fails. But in all instances set.sig[1] gets >> initialized. >> >>> I don't have enough time to look at this right now, sorry. >>> >>> Another question, __copy_from_user() will be called even if >>> _NSIG_WORDS is less than 2, perhaps it never occurs. >>> I think, to check _NSIG_WORDS > 1 before calling __copy_from_user() >>> is better. >> Fine. Let Ingo/Thomas/Peter decide whether they would like this fix or >> drop it. > > If you get the Acked-by from Hiroshi-san it looks good to me. He > modified this code last. >
This seriously looks wrong to me. If _NSIG_WORDS == 1, then calling __copy_from_user here is a serious error.
-hpa
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