Bug 70277 – zdiff bug in gzip-1.3.5-r2

• Product: Gentoo Linux
• Status: VERIFIED FIXED

[Description Michael Moen 2004-11-06 09:48:54 UTC]

When trying to use zdiff on 2 gzipped files (works fine when only one file is gzipped) you get the following error:

/bin/zdiff: line 54: /tmp/gzcuA0AB: cannot overwrite existing file

Possibly related to bug #68405

uname -a
Linux xxxx 2.4.25_pre7-gss-r2 #2 SMP Tue Mar 2 06:45:59 PST 2004 i686 AMD Athlon(tm) MP 2400+ AuthenticAMD GNU/Linux

[Comment 1 solar (RETIRED) 2004-11-17 13:34:09 UTC]

gzip-r4 in the tree. No patch for this. Remains problem (security bug?)

[Comment 2 Florian Schilhabel (RETIRED) 2004-11-18 06:02:12 UTC]

hi,
i guess, the problem is here:
line 37:
tmp=`tempfile -d /tmp -p gz` || {
...
this actually _creates_ a temporary file...
and this behaviour of tempfile is the reason, why
line 53:
gzip -cdfq "$2" > $tmp || exit
(correctly) refuses to extract to an existing file...

solution:

one could unlink the tempfile after creating it with tempfile
note, that this solution would introduce (theoretically) a race condition...
(an attacker knows the tempfilename after unlinking and _before_ actually writing to that file)
as gzip refuses to extract, if the file already exists, i guess this would be a 
good solution anyways...

further comments?

best regards
florian

[Comment 3 SpanKY 2004-12-12 20:33:18 UTC]

fixed in 1.3.5-r4

[Comment 4 Michael Moen 2004-12-15 22:46:32 UTC]

Still does not work when comparing 2 gzipped files.

zdiff mysql-2004-11-13-170003.sql.gz mysql-2004-12-08-140005.sql.gz
/bin/zdiff: line 51: /tmp/mysql2004-12-08-140005.sql.gz.52jbkt: cannot overwrite existing file

And now that gzip-1.3.5-r1 has been removed from the tree I don't have a working version of gzip.

[Comment 5 SpanKY 2005-01-04 11:28:15 UTC]

fixed in gzip-1.3.5-r5

[Comment 6 Michael Moen 2005-01-06 18:39:43 UTC]

Confirmed fixed in gzip-1.3.5-r5