On Tue, Mar 19, 2013 at 11:42:45AM +0100, Bernhard Posselt wrote:
> it seems that the memory corruption does not happen anymore when i change
>
> [apply]
> whitespace = fix
>
> to
>
> [apply]
> #whitespace = fix
>
> so fixing whitespaces may be the culprit
Thanks, I'm able to reproduce with the config you showed. The other key
element seems to be using tab-in-indent. I am not too familiar with
this code, but I was able to get a much smaller reproduction recipe:
-- >8 --
# make tabs more obvious by using "Q" instead
q_to_tab() {
perl -lpe 's/Q/\t/g'
}
q_to_tab >preimage <<\EOF
QQa
QQb
QQc
d
QQe
QQf
QQg
EOF
q_to_tab >patch <<\EOF
diff --git a/preimage b/preimage
--- a/preimage
+++ b/preimage
@@ -1,7 +1,6 @@ public static function store($filename) {
QQa
QQb
QQc
-QQd
QQe
QQf
QQg
EOF
valgrind \
git -c core.whitespace=tab-in-indent apply --whitespace=fix patch
-- 8< --
which yields:
==7112== Invalid write of size 2
==7112== at 0x4C2C023: memcpy (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==7112== by 0x40C365: update_pre_post_images (apply.c:2165)
==7112== by 0x40CC52: match_fragment (apply.c:2402)
[...]
==7112== Address 0x6e57a5e is 0 bytes after a block of size 94 alloc'd
==7112== at 0x4C2A26B: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==7112== by 0x4C2A51F: realloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==7112== by 0x535193: xrealloc (wrapper.c:100)
==7112== by 0x51C322: strbuf_grow (strbuf.c:74)
==7112== by 0x51C10C: strbuf_init (strbuf.c:34)
==7112== by 0x40D329: apply_one_fragment (apply.c:2602)
[...]
and so on. I haven't quite figured out what is going on. It looks like
we call update_pre_post_images with postlen==0, which causes it to just
write the fixed postimage into the existing buffer. But of course the
fixed version is bigger, because we are expanding the tabs into 8
spaces (but it _doesn't_ break if each line starts with only one tab,
which confuses me).
I'm not too familiar with this code. Maybe Junio can say more.
-Peff
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