# Do not use zlib 1.1.3 with git packs! 4 messages from 2006-04-29 to 2006-04-29. Participants: Johannes Schindelin, Nicolas Pitre, Junio C Hamano. Thread: https://gitlist.dev/t/3992 ## Johannes Schindelin, 2006-04-29 00:52 Subject: Do not use zlib 1.1.3 with git packs! Message-ID: URL: https://gitlist.dev/e/Pine.LNX.4.63.0604290245510.30565%40wbgn013.biozentrum.uni-wuerzburg.de ``` Hi, I had a strange effect when trying to repack a git repository on my iBook: first, "git-repack -a -d" would quit without an error message when about 57% of the objects were written (*not* when deltifying them!). It became even stranger when I tracked it to a segmentation fault in adler32(), where the debugger insisted that a buffer was NULL, but the calling code insisted it was not. Upgrading to zlib 1.2.3 helped. That is, after I had a complete systen fsck-up, since virtually every binary, including su, login and getty, are linked to zlib on Mac OS X. (Yeah, yeah, no Linux, I know.) Ciao, Dscho P.S.: This _might_ be related to the git-repack issue that came up a few days ago. ``` ## Johannes Schindelin, 2006-04-29 01:47 Subject: Re: Do not use zlib 1.1.3 with git packs! Message-ID: URL: https://gitlist.dev/e/Pine.LNX.4.63.0604290341380.22696%40wbgn013.biozentrum.uni-wuerzburg.de In-Reply-To: ``` Hi, On Sat, 29 Apr 2006, Johannes Schindelin wrote: > Upgrading to zlib 1.2.3 helped. Apparently I was too enthusiastic to have a working system again. The problem showed again, but with a different repository. This time, though, I have an idea what could be the culprit. In create_delta(), there might be illegal accesses. The function adler32() is called for BLK_SIZE bytes (which is 16 bytes at the moment), starting from data, which is initially trg_buf, and is incremented until it is (trg_buf + trg_size). I gather that close to the end, adler32() tries to read 15 bytes after the end of the allocated target buffer. Am I wrong? Ciao, Dscho ``` ## Nicolas Pitre, 2006-04-29 03:20 Subject: Re: Do not use zlib 1.1.3 with git packs! Message-ID: URL: https://gitlist.dev/e/Pine.LNX.4.64.0604282316520.18816%40localhost.localdomain In-Reply-To: ``` On Sat, 29 Apr 2006, Johannes Schindelin wrote: > Hi, > > On Sat, 29 Apr 2006, Johannes Schindelin wrote: > > > Upgrading to zlib 1.2.3 helped. > > Apparently I was too enthusiastic to have a working system again. > > The problem showed again, but with a different repository. > > This time, though, I have an idea what could be the culprit. > > In create_delta(), there might be illegal accesses. The function adler32() > is called for BLK_SIZE bytes (which is 16 bytes at the moment), starting > from data, which is initially trg_buf, and is incremented until it is > (trg_buf + trg_size). > > I gather that close to the end, adler32() tries to read 15 bytes after the > end of the allocated target buffer. > > Am I wrong? You're not. My bad. (I'm testing a version where adler32 has been replaced with rabin polynomial so that issue will be gone at the same time. A patch should be coming in less than an hour.) Nicolas ``` ## Junio C Hamano, 2006-04-29 06:36 Subject: Re: Do not use zlib 1.1.3 with git packs! Message-ID: <7vvessanx1.fsf@assigned-by-dhcp.cox.net> URL: https://gitlist.dev/e/7vvessanx1.fsf%40assigned-by-dhcp.cox.net In-Reply-To: ``` Nicolas Pitre writes: > On Sat, 29 Apr 2006, Johannes Schindelin wrote: > >> I gather that close to the end, adler32() tries to read 15 bytes after the >> end of the allocated target buffer. >> >> Am I wrong? > > You're not. My bad. Thanks both, for catching this while still in "next". ```