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December 2010
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2010.12.08 01:19 "Re: Security vulnerability CVE-2010-3847", by Lee Howard
Tom Lane wrote: > Lee Howard <faxguy@howardsilvan.com> writes: > >> I've just now committed the in-line patch found on... >> > > >> http://bugzilla.maptools.org/show_bug.cgi?id=2228 >> > > I find the patch given in #2228 pretty unsatisfactory, as it's > throwing away image quality to produce what seems no better than a > cargo-cult solution to the problem. Turning off fancy upsampling > doesn't affect the number of output pixels libjpeg produces. It > would cause it to not *read* adjacent rows for averaging purposes, > but if that causes a segfault then your problem is elsewhere. > It is certainly not fixing the problem explained in #2140, which > is that the required output buffer size is underestimated. > Very well. I've backed-out (undone) the patch. For what it's worth, the various distros (well, SUSE at least) were applying that patch as well as the one from 2140. >> ... I'm not sure if that small change resolves CVE-2010-3087. The >> various distros are using Tom Lane's patch on... >> > > >> http://bugzilla.maptools.org/show_bug.cgi?id=2140 >> > > >> ... as a resolution to CVE-2010-3087. >> > > >> You can see on the bug report that Frank seemed to object to Tom's >> proposal on Bug 2140, so I think for the moment we're stuck there >> needing some further response from Frank on this. (Frank?) >> > > For the record, *I* don't much like that patch either :-). I think it's > OK for the limited purpose of stopping core dumps, but it's far from > resolving all the issues complained of in #2140. Thanks for your comments. I've applied and committed the 2140 patch to the 3.9 branch. The patch does not apply at all to tif_strip.c in HEAD (4.0). However, the segfault does not occur there... [root@gollum libtiff]# tools/tiffcmp -l /tmp/libtiffpic/quad-jpeg.tif /tmp/libtiffpic/quad-jpeg.tif ; echo $? TIFFReadScanline: scanline oriented access is not supported for downsampled JPEG compressed images, consider enabling TIFF_JPEGCOLORMODE as JPEGCOLORMODE_RGB.. /tmp/libtiffpic/quad-jpeg.tif: EOF at scanline 0 0 [root@gollum libtiff]# I suspect that this result with HEAD is satisfactory since the aim of the 3.9 patching was to avoid the crash. Thanks, Lee.