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authorDaniel Borkmann <dborkman@redhat.com>2014-08-26 23:16:35 -0400
committerTheodore Ts'o <tytso@mit.edu>2014-10-17 11:37:29 -0400
commitd4c5efdb97773f59a2b711754ca0953f24516739 (patch)
tree83ededeb92d6d529e8081b97b2f9cdf491094b78 /drivers/char/random.c
parent7d1311b93e58ed55f3a31cc8f94c4b8fe988a2b9 (diff)
downloadleg-kernel-d4c5efdb97773f59a2b711754ca0953f24516739.tar.gz
random: add and use memzero_explicit() for clearing data
zatimend has reported that in his environment (3.16/gcc4.8.3/corei7) memset() calls which clear out sensitive data in extract_{buf,entropy, entropy_user}() in random driver are being optimized away by gcc. Add a helper memzero_explicit() (similarly as explicit_bzero() variants) that can be used in such cases where a variable with sensitive data is being cleared out in the end. Other use cases might also be in crypto code. [ I have put this into lib/string.c though, as it's always built-in and doesn't need any dependencies then. ] Fixes kernel bugzilla: 82041 Reported-by: zatimend@hotmail.co.uk Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@vger.kernel.org
Diffstat (limited to 'drivers/char/random.c')
-rw-r--r--drivers/char/random.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/char/random.c b/drivers/char/random.c
index c18d41db83d8..8c86a95203a0 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1106,7 +1106,7 @@ static void extract_buf(struct entropy_store *r, __u8 *out)
__mix_pool_bytes(r, hash.w, sizeof(hash.w));
spin_unlock_irqrestore(&r->lock, flags);
- memset(workspace, 0, sizeof(workspace));
+ memzero_explicit(workspace, sizeof(workspace));
/*
* In case the hash function has some recognizable output
@@ -1118,7 +1118,7 @@ static void extract_buf(struct entropy_store *r, __u8 *out)
hash.w[2] ^= rol32(hash.w[2], 16);
memcpy(out, &hash, EXTRACT_SIZE);
- memset(&hash, 0, sizeof(hash));
+ memzero_explicit(&hash, sizeof(hash));
}
/*
@@ -1175,7 +1175,7 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf,
}
/* Wipe data just returned from memory */
- memset(tmp, 0, sizeof(tmp));
+ memzero_explicit(tmp, sizeof(tmp));
return ret;
}
@@ -1218,7 +1218,7 @@ static ssize_t extract_entropy_user(struct entropy_store *r, void __user *buf,
}
/* Wipe data just returned from memory */
- memset(tmp, 0, sizeof(tmp));
+ memzero_explicit(tmp, sizeof(tmp));
return ret;
}