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| author | Herbert Xu <herbert@gondor.apana.org.au> | 2017-04-27 13:44:51 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-04-27 11:48:24 -0400 |
| commit | 6d684e54690caef45cf14051ddeb7c71beeb681b (patch) | |
| tree | 1544faf80a19bf2fa47d9f2a1e5f2f98dbb17545 /lib/rhashtable.c | |
| parent | 4b726e81dab2cefefd2c1cb00e3074ac0eec4b15 (diff) | |
| download | linux-6d684e54690caef45cf14051ddeb7c71beeb681b.tar.gz linux-6d684e54690caef45cf14051ddeb7c71beeb681b.tar.bz2 linux-6d684e54690caef45cf14051ddeb7c71beeb681b.zip | |
rhashtable: Cap total number of entries to 2^31
When max_size is not set or if it set to a sufficiently large
value, the nelems counter can overflow. This would cause havoc
with the automatic shrinking as it would then attempt to fit a
huge number of entries into a tiny hash table.
This patch fixes this by adding max_elems to struct rhashtable
to cap the number of elements. This is set to 2^31 as nelems is
not a precise count. This is sufficiently smaller than UINT_MAX
that it should be safe.
When max_size is set max_elems will be lowered to at most twice
max_size as is the status quo.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'lib/rhashtable.c')
| -rw-r--r-- | lib/rhashtable.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/lib/rhashtable.c b/lib/rhashtable.c index f3b82e0d417b..751630bbe409 100644 --- a/lib/rhashtable.c +++ b/lib/rhashtable.c @@ -961,6 +961,11 @@ int rhashtable_init(struct rhashtable *ht, if (params->max_size) ht->p.max_size = rounddown_pow_of_two(params->max_size); + /* Cap total entries at 2^31 to avoid nelems overflow. */ + ht->max_elems = 1u << 31; + if (ht->p.max_size < ht->max_elems / 2) + ht->max_elems = ht->p.max_size * 2; + ht->p.min_size = max(ht->p.min_size, HASH_MIN_SIZE); if (params->nelem_hint) |