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Subject[PATCH 2/8] Replace memset() with memzero_explicit()
Replace memset(address,0,bytes) which may be optimised away
with memzero_explicit(address,bytes) which resists
such optimisation

---
crypto/drbg.c | 25 ++++++++++++-------------
1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/crypto/drbg.c b/crypto/drbg.c
index f72f340a1321..08c4586a4cc9 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -507,9 +507,9 @@ static int drbg_ctr_df(struct drbg_state *drbg,
ret = 0;

out:
- memset(iv, 0, drbg_blocklen(drbg));
- memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
- memset(pad, 0, drbg_blocklen(drbg));
+ memzero_explicit(iv, drbg_blocklen(drbg));
+ memzero_explicit(temp, drbg_statelen(drbg) + drbg_blocklen(drbg));
+ memzero_explicit(pad, drbg_blocklen(drbg));
return ret;
}

@@ -580,9 +580,9 @@ 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;
}

@@ -852,7 +852,7 @@ static int drbg_hash_df(struct drbg_state *drbg,
}

out:
- memset(tmp, 0, drbg_blocklen(drbg));
+ memzero_explicit(tmp, drbg_blocklen(drbg));
return ret;
}

@@ -895,7 +895,7 @@ 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;
}

@@ -927,7 +927,7 @@ 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;
}

@@ -967,8 +967,7 @@ static int drbg_hash_hashgen(struct drbg_state *drbg,
}

out:
- memset(drbg->scratchpad, 0,
- (drbg_statelen(drbg) + drbg_blocklen(drbg)));
+ memzero_explicit(drbg->scratchpad, (drbg_statelen(drbg) +
drbg_blocklen(drbg)));
return len;
}

@@ -1015,7 +1014,7 @@ 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;
}

@@ -1202,8 +1201,8 @@ static int drbg_seed(struct drbg_state *drbg,
struct drbg_string *pers,
}

if (!reseed) {
- memset(drbg->V, 0, drbg_statelen(drbg));
- memset(drbg->C, 0, drbg_statelen(drbg));
+ memzero_explicit(drbg->V, drbg_statelen(drbg));
+ memzero_explicit(drbg->C, drbg_statelen(drbg));
}

ret = __drbg_seed(drbg, &seedlist, reseed);
--
2.25.1
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