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| author | Andy Whitcroft <apw@shadowen.org> | 2007-05-15 17:33:25 +0100 |
|---|---|---|
| committer | Junio C Hamano <junkio@cox.net> | 2007-05-15 18:14:42 -0700 |
| commit | cf606e3ddd8666b990a6560be77eb9f28af0e47d (patch) | |
| tree | 4cf1c85058ac12ff55e61870b5220b5f7c2d000a /git-compat-util.h | |
| parent | 045fe3ccdaeb81f12f657b44b5a117b65d9d38e2 (diff) | |
| download | git-cf606e3ddd8666b990a6560be77eb9f28af0e47d.tar.gz git-cf606e3ddd8666b990a6560be77eb9f28af0e47d.tar.xz | |
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.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/git-compat-util.h b/git-compat-util.h index bd93b6257..7ed8b88b1 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 */ |