From fb38ab4cd05e11184fd2c3ef916fa106ecc505fc Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Fri, 5 Sep 2014 15:52:28 +0800 Subject: [PATCH] crypto: drbg - backport "fix maximum value checks on 32 bit systems" This is a backport of commit b9347aff91ce4789619168539f08202d8d6a1177. 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 Reported-by: kbuild test robot Signed-off-by: Herbert Xu --- include/crypto/drbg.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/include/crypto/drbg.h b/include/crypto/drbg.h index 831d786976c5..882675e7c055 100644 --- a/include/crypto/drbg.h +++ b/include/crypto/drbg.h @@ -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 } /* -- 2.20.1