Commit ece482ff authored by Dr. Matthias St. Pierre's avatar Dr. Matthias St. Pierre
Browse files

RAND_add(): fix heap corruption in error path 



This bug was introduced by #7382 which enhanced RAND_add() to
accept large buffer sizes. As a consequence, RAND_add() now fails
for buffer sizes less than 32 bytes (i.e. less than 256 bits).
In addition, rand_drbg_get_entropy() forgets to reset the attached
drbg->pool in the case of an error, which leads to the heap corruption.

The problem occurred with RAND_load_file(), which reads the file in
chunks of 1024 bytes each. If the size of the final chunk is less than
32 bytes, then RAND_add() fails, whence RAND_load_file() fails
silently for buffer sizes n = k * 1024 + r with r = 1,...,31.

This commit fixes the heap corruption only. The other issues will
be addressed in a separate pull request.

Thanks to Gisle Vanem for reporting this issue.

Fixes #7449

Reviewed-by: default avatarPaul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/7455)

(cherry picked from commit 5b4cb385c18a5bb4e118e300f1c746bf7c2a5628)
parent 132fd512

crypto/rand/rand_lib.c

+4 −0
Original line number Diff line number Diff line
@@ -200,6 +200,10 @@ size_t rand_drbg_get_entropy(RAND_DRBG *drbg, 
    }



 err:

    /* we need to reset drbg->pool in the error case */

    if (ret == 0 && drbg->pool != NULL)

        drbg->pool = NULL;



    rand_pool_free(pool);

    return ret;

}