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Commit 421d82f5 authored by Nickolaus Woodruff's avatar Nickolaus Woodruff Committed by Herbert Xu
Browse files

crypto: drbg - use memzero_explicit() for clearing sensitive data 



Compiler dead store optimization can sometimes remove final calls
to memset() used to clear sensitive data at the end of a function.
Replace trailing memset() calls with memzero_explicit() to
preclude unwanted removal.

Signed-off-by: default avatarNickolaus Woodruff <nickolauswoodruff@gmail.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 0653a7cf

crypto/drbg.c

+12 −11
Original line number Diff line number Diff line
@@ -98,6 +98,7 @@ 
 */



#include <crypto/drbg.h>

#include <linux/string.h>



/***************************************************************

 * Backend cipher definitions available to DRBG
@@ -497,9 +498,9 @@ static int drbg_ctr_df(struct drbg_state *drbg, 
	ret = 0;



out:

	memset(iv, 0, drbg_blocklen(drbg));

	memset(temp, 0, drbg_statelen(drbg));

	memset(pad, 0, drbg_blocklen(drbg));

	memzero_explicit(iv, drbg_blocklen(drbg));

	memzero_explicit(temp, drbg_statelen(drbg));

	memzero_explicit(pad, drbg_blocklen(drbg));

	return ret;

}
@@ -573,9 +574,9 @@ static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed, 
	ret = 0;



out:

	memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));

	memzero_explicit(temp, drbg_statelen(drbg) + drbg_blocklen(drbg));

	if (2 != reseed)

		memset(df_data, 0, drbg_statelen(drbg));

		memzero_explicit(df_data, drbg_statelen(drbg));

	return ret;

}
@@ -633,7 +634,7 @@ static int drbg_ctr_generate(struct drbg_state *drbg, 
		len = ret;



out:

	memset(drbg->scratchpad, 0, drbg_blocklen(drbg));

	memzero_explicit(drbg->scratchpad, drbg_blocklen(drbg));

	return len;

}
@@ -871,7 +872,7 @@ static int drbg_hash_df(struct drbg_state *drbg, 
	}



out:

	memset(tmp, 0, drbg_blocklen(drbg));

	memzero_explicit(tmp, drbg_blocklen(drbg));

	return ret;

}
@@ -915,7 +916,7 @@ static int drbg_hash_update(struct drbg_state *drbg, struct list_head *seed, 
	ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &datalist2);



out:

	memset(drbg->scratchpad, 0, drbg_statelen(drbg));

	memzero_explicit(drbg->scratchpad, drbg_statelen(drbg));

	return ret;

}
@@ -950,7 +951,7 @@ static int drbg_hash_process_addtl(struct drbg_state *drbg, 
		     drbg->scratchpad, drbg_blocklen(drbg));



out:

	memset(drbg->scratchpad, 0, drbg_blocklen(drbg));

	memzero_explicit(drbg->scratchpad, drbg_blocklen(drbg));

	return ret;

}
@@ -997,7 +998,7 @@ static int drbg_hash_hashgen(struct drbg_state *drbg, 
	}



out:

	memset(drbg->scratchpad, 0,

	memzero_explicit(drbg->scratchpad,

	       (drbg_statelen(drbg) + drbg_blocklen(drbg)));

	return len;

}
@@ -1046,7 +1047,7 @@ static int drbg_hash_generate(struct drbg_state *drbg, 
	drbg_add_buf(drbg->V, drbg_statelen(drbg), u.req, 8);



out:

	memset(drbg->scratchpad, 0, drbg_blocklen(drbg));

	memzero_explicit(drbg->scratchpad, drbg_blocklen(drbg));

	return len;

}