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crypto: drbg - backport "fix maximum value checks on 32 bit systems"

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This is a backport of commit b9347aff91.
This backport is needed as without it the code will crash on 32-bit
systems.
    
The maximum values for additional input string or generated blocks is
larger than 1<<32. To ensure a sensible value on 32 bit systems, return
SIZE_MAX on 32 bit systems. This value is lower than the maximum
allowed values defined in SP800-90A. The standard allow lower maximum
values, but not larger values.

SIZE_MAX - 1 is used for drbg_max_addtl to allow
drbg_healthcheck_sanity to check the enforcement of the variable
without wrapping.
    
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Herbert Xu 2014-09-05 15:52:28 +08:00
parent 7d1311b93e
commit fb38ab4cd0
1 changed files with 13 additions and 0 deletions
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13
include/crypto/drbg.h
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@ -162,12 +162,25 @@ static inline size_t drbg_max_request_bytes(struct drbg_state *drbg)
static inline size_t drbg_max_addtl(struct drbg_state *drbg)
{
#if (__BITS_PER_LONG == 32)
/*
* SP800-90A allows smaller maximum numbers to be returned -- we
* return SIZE_MAX - 1 to allow the verification of the enforcement
* of this value in drbg_healthcheck_sanity.
*/
return (SIZE_MAX - 1);
#else
return (1UL<<(drbg->core->max_addtllen));
#endif
}
static inline size_t drbg_max_requests(struct drbg_state *drbg)
{
#if (__BITS_PER_LONG == 32)
return SIZE_MAX;
#else
return (1UL<<(drbg->core->max_req));
#endif
}
/*