Commit fb38ab4c authored Sep 05, 2014 by Herbert Xu

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



This is a backport of commit b9347aff.
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>

parent 7d1311b9

include/crypto/drbg.h

+13 −0

Original line number	Diff line number	Diff line
		@@ -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
		}

		/*