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[CCID3] Avoid unsigned integer overflows in usecs_div

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Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
This commit is contained in:
Arnaldo Carvalho de Melo
2005-09-09 02:28:47 -03:00
parent e104411b82
commit 0ba7a3ba66
1 changed files with 13 additions and 3 deletions
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16
net/dccp/ccids/ccid3.c
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@ -43,12 +43,22 @@
#include "ccid3.h" #include "ccid3.h"
/* /*
* Reason for maths with 10 here is to avoid 32 bit overflow when a is big. * Reason for maths here is to avoid 32 bit overflow when a is big.
* With this we get close to the limit.
*/ */
static inline u32 usecs_div(const u32 a, const u32 b) static inline u32 usecs_div(const u32 a, const u32 b)
{ {
const u32 tmp = a * (USEC_PER_SEC / 10); const u32 div = a < (UINT_MAX / (USEC_PER_SEC / 10)) ? 10 :
return b > 20 ? tmp / (b / 10) : tmp; a < (UINT_MAX / (USEC_PER_SEC / 50)) ? 50 :
a < (UINT_MAX / (USEC_PER_SEC / 100)) ? 100 :
a < (UINT_MAX / (USEC_PER_SEC / 500)) ? 500 :
a < (UINT_MAX / (USEC_PER_SEC / 1000)) ? 1000 :
a < (UINT_MAX / (USEC_PER_SEC / 5000)) ? 5000 :
a < (UINT_MAX / (USEC_PER_SEC / 10000)) ? 10000 :
a < (UINT_MAX / (USEC_PER_SEC / 50000)) ? 50000 :
100000;
const u32 tmp = a * (USEC_PER_SEC / div);
return (b >= 2 * div) ? tmp / (b / div) : tmp;
} }
static int ccid3_debug; static int ccid3_debug;