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Fix a race condition in drbg_add

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Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/7523)

(cherry picked from commit 4011bab1f8)
This commit is contained in:
Bernd Edlinger 2018-10-29 13:48:53 +01:00
parent de8848aeaf
commit faca6bfac3
1 changed files with 5 additions and 2 deletions
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7
crypto/rand/drbg_lib.c
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@ -1003,6 +1003,7 @@ static int drbg_add(const void *buf, int num, double randomness)
if (num < 0 || randomness < 0.0) if (num < 0 || randomness < 0.0)
return 0; return 0;
rand_drbg_lock(drbg);
seedlen = rand_drbg_seedlen(drbg); seedlen = rand_drbg_seedlen(drbg);
buflen = (size_t)num; buflen = (size_t)num;
@ -1014,10 +1015,13 @@ static int drbg_add(const void *buf, int num, double randomness)
* inevitably. So we use a trick to mix the buffer contents into * inevitably. So we use a trick to mix the buffer contents into
* the DRBG state without forcing a reseeding: we generate a * the DRBG state without forcing a reseeding: we generate a
* dummy random byte, using the buffer content as additional data. * dummy random byte, using the buffer content as additional data.
* Note: This won't work with RAND_DRBG_FLAG_CTR_NO_DF.
*/ */
unsigned char dummy[1]; unsigned char dummy[1];
return RAND_DRBG_generate(drbg, dummy, sizeof(dummy), 0, buf, buflen); ret = RAND_DRBG_generate(drbg, dummy, sizeof(dummy), 0, buf, buflen);
rand_drbg_unlock(drbg);
return ret;
#else #else
/* /*
* If an os entropy source is avaible then we declare the buffer content * If an os entropy source is avaible then we declare the buffer content
@ -1041,7 +1045,6 @@ static int drbg_add(const void *buf, int num, double randomness)
randomness = (double)seedlen; randomness = (double)seedlen;
} }
rand_drbg_lock(drbg);
ret = rand_drbg_restart(drbg, buf, buflen, (size_t)(8 * randomness)); ret = rand_drbg_restart(drbg, buf, buflen, (size_t)(8 * randomness));
rand_drbg_unlock(drbg); rand_drbg_unlock(drbg);