[Rd] Bug in R 2.7 for over long lines (crasher+proposed fix!) (PR#11281)

[maechler at stat.math.ethz.ch]

Hi Soeren,
>>>>> "SS" == Soeren Sonnenburg <bugreports at nn7.de>
>>>>>     on Sat, 10 May 2008 05:32:14 +0000 writes:

    SS> On Sat, 2008-04-26 at 09:38 +0200, Peter Dalgaard wrote:
    >> bugreports at nn7.de wrote: > OK, I am just sending it here
    >> too as it looks like r-devel at r-project.org > is not the
    >> right place:
    >> >   
    >> I think it was seen there too, just that noone got around
    >> to reply. In R-bugs, there's a filing system so that it
    >> won't be completely forgotten...

    SS> Looks like no one cares about this :(

Just "looks like" but it aint...

    SS> What should I do now? I mean I pointed directly to the
    SS> bug and did show how it could be fixed....

I'm not among the parse experts within R-core, but I think the
main problem with your report is that 
you talk about a crash but do not provide "self-contained
reproducible" code to produce such a crash, but just the
assertion that you get crashes when working on R <-> Swig
interaction.
Can you construct simple R code producing the crash?

Best regards
Martin


    >> However, your mail seems to have gotten encoded in
    >> quoted-printable, you might want to follow up with a
    >> cleaned version. (Just keep the (PR#11281) in the
    >> header).

    SS> To me crashers are critical bugs... isn't really no one
    SS> interested in seeing this fixed?

    >> > =EF=BB=BFOn Fri, 2008-04-25 at 08:48 +0200, Soeren
    >> Sonnenburg wrote:
    >> >   
    >> >> While trying to fix swig & R2.7 I actually discovered
    >> that there is a >> bug in R 2.7 causing a crash (so R &
    >> swig might actually work): >> =20 >> the bug is in
    >> ./src/main/gram.c line 3038: >> =20 >> } else { /*
    >> over-long line */ >> fixthis --> char *LongLine =3D (char
    >> *) malloc(nc); >> if(!LongLine) >> error(_("unable to
    >> allocate space for source line %
    >> >>     
    >> > d"), xxlineno);
    >> >   
    >> >> strncpy(LongLine, (char *)p0, nc); >> bug -->
    >> LongLine[nc] =3D '\0'; >> SET_STRING_ELT(source, lines++,
    >> >> mkChar2((char *)LongLine)); >> free(LongLine); >> =20
    >> >> note that LongLine is only nc chars long, so the
    >> LongLine[nc]=3D'\0'
    >> >>     
    >> > might
    >> >   
    >> >> be an out of bounds write. the fix would be to do >>
    >> =20 >> =EF=BB=BF char *LongLine =3D (char *)
    >> malloc(nc+1); >> =20 >> in line 3034 >> =20 >> Please fix
    >> and thanks to dirk for the debian r-base-dbg package!
    >> >>     
    >> >
    >> > Looking at the code again there seems to be another bug
    >> above this for > the MAXLINESIZE test too:
    >> >
    >> > if (*p =3D=3D '\n' || p =3D=3D end - 1) { > nc =3D p -
    >> p0; > if (*p !=3D '\n') > nc++; > if (nc <=3D
    >> MAXLINESIZE) { > strncpy((char *)SourceLine, (char *)p0,
    >> nc); > bug2 --> SourceLine[nc] =3D '\0'; >
    >> SET_STRING_ELT(source, lines++, > mkChar2((char
    >> *)SourceLine)); > } else { /* over-long line */ > char
    >> *LongLine =3D (char *) malloc(nc+1); > if(!LongLine) >
    >> error(_("unable to allocate space for source line %d"), >
    >> xxlineno); > bug1 --> strncpy(LongLine, (char *)p0, nc);
    >> > LongLine[nc] =3D '\0'; > SET_STRING_ELT(source,
    >> lines++, > mkChar2((char *)LongLine)); > free(LongLine);
    >> > } > p0 =3D p + 1; > }
    >> >
    >> >
    >> > So I guess the test would be for nc < MAXLINESIZE above
    >> or to change > SourceLine to have MAXLINESIZE+1 size.
    >> >
    >> > Alternatively as the strncpy manpage suggests do this
    >> for all > occurrences of strncpy
    >> >
    >> > strncpy(buf, str, n); > if (n > 0) > buf[n - 1]=3D
    >> =E2=80=99\0=E2=80=99;
    >> >
    >> > this could even be made a makro / helper function ...
    >> >
    >> > And another update: This does fix the R+swig crasher
    >> for me (tested)!
    >> >
    >> > Soeren

    SS> Soeren

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