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authorAndy Whitcroft <apw@shadowen.org>2007-05-15 16:33:25 (GMT)
committerJunio C Hamano <junkio@cox.net>2007-05-16 01:14:42 (GMT)
commitcf606e3ddd8666b990a6560be77eb9f28af0e47d (patch)
tree4cf1c85058ac12ff55e61870b5220b5f7c2d000a /git-compat-util.h
parent045fe3ccdaeb81f12f657b44b5a117b65d9d38e2 (diff)
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git name-rev writes beyond the end of malloc() with large generations
When using git name-rev on my kernel tree I triggered a malloc() corruption warning from glibc. apw@pinky$ git log --pretty=one $N/base.. | git name-rev --stdin *** glibc detected *** malloc(): memory corruption: 0x0bff8950 *** Aborted This comes from name_rev() which is building the name of the revision in a malloc'd string, which it sprintf's into: char *new_name = xmalloc(len + 8); [...] sprintf(new_name, "%.*s~%d^%d", len, tip_name, generation, parent_number); This allocation is only sufficient if the generation number is less than 5 digits, in my case generation was 13432. In reality parent_number can be up to 16 so that also can require two digits, reducing us to 3 digits before we are at risk of blowing this allocation. This patch introduces a decimal_length() which approximates the number of digits a type may hold, it produces the following: Type Longest Value Len Est ---- ------------- --- --- unsigned char 256 3 4 unsigned short 65536 5 6 unsigned long 4294967296 10 11 unsigned long long 18446744073709551616 20 21 char -128 4 4 short -32768 6 6 long -2147483648 11 11 long long -9223372036854775808 20 21 This is then used to size the new_name. Signed-off-by: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
Diffstat (limited to 'git-compat-util.h')
-rw-r--r--git-compat-util.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/git-compat-util.h b/git-compat-util.h
index bd93b62..7ed8b88 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -13,6 +13,9 @@
#define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))
+/* Approximation of the length of the decimal representation of this type. */
+#define decimal_length(x) ((int)(sizeof(x) * 2.56 + 0.5) + 1)
+
#if !defined(__APPLE__) && !defined(__FreeBSD__)
#define _XOPEN_SOURCE 600 /* glibc2 and AIX 5.3L need 500, OpenBSD needs 600 for S_ISLNK() */
#define _XOPEN_SOURCE_EXTENDED 1 /* AIX 5.3L needs this */