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| author | Arnaldo Carvalho de Melo <acme@mandriva.com> | 2005-09-09 02:28:47 -0300 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@mandriva.com> | 2005-09-09 02:28:47 -0300 |
| commit | 0ba7a3ba6608de6e0c0bfe3009a63d7e0b7ab0ce (patch) | |
| tree | db5b9c5a778e0cbc08bcbf7f5b25174499b13a1d /net | |
| parent | e104411b82f5c4d19752c335492036abdbf5880d (diff) | |
| download | linux-0ba7a3ba6608de6e0c0bfe3009a63d7e0b7ab0ce.tar.bz2 | |
[CCID3] Avoid unsigned integer overflows in usecs_div
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Diffstat (limited to 'net')
| -rw-r--r-- | net/dccp/ccids/ccid3.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c index 7bf3b3a91e97..ae0500c79d07 100644 --- a/net/dccp/ccids/ccid3.c +++ b/net/dccp/ccids/ccid3.c @@ -43,12 +43,22 @@ #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) { - const u32 tmp = a * (USEC_PER_SEC / 10); - return b > 20 ? tmp / (b / 10) : tmp; + const u32 div = a < (UINT_MAX / (USEC_PER_SEC / 10)) ? 10 : + 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; |