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lib: constrain hash table "tabshift" both ways 

The previous change to assume() did address the coverity warning about
one direction of the shift in HASH_KEY, let's constrain the other in
HASH_SIZE as well.

To be fair, the hash table *will* break at 1G entries, but at that point
we have other problems RAM-wise.  (Could bump the thing to 64-bit, but
then we need better item hash functions too on every single user.)

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
This commit is contained in:
David Lamparter 2023-09-19 21:03:24 +02:00
parent e7f0bbb198
commit e7737c89eb
1 changed files with 6 additions and 3 deletions
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9
lib/typesafe.h
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@ -795,13 +795,16 @@ struct thash_head {
uint8_t minshift, maxshift;
};
#define _HASH_SIZE(tabshift) \
((1U << (tabshift)) >> 1)
#define _HASH_SIZE(tabshift) \
({ \
assume((tabshift) <= 31); \
(1U << (tabshift)) >> 1; \
})
#define HASH_SIZE(head) \
_HASH_SIZE((head).tabshift)
#define _HASH_KEY(tabshift, val) \
({ \
assume((tabshift) >= 2 && (tabshift) <= 33); \
assume((tabshift) >= 2 && (tabshift) <= 31); \
(val) >> (33 - (tabshift)); \
})
#define HASH_KEY(head, val) \