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    • Matt Caswell's avatar
      Fix buffer overrun in RSA signing · 34166d41
      Matt Caswell authored
      
      
      The problem occurs in EVP_PKEY_sign() when using RSA with X931 padding.
      It is only triggered if the RSA key size is smaller than the digest length.
      So with SHA512 you can trigger the overflow with anything less than an RSA
      512 bit key. I managed to trigger a 62 byte overflow when using a 16 bit RSA
      key. This wasn't sufficient to cause a crash, although your mileage may
      vary.
      
      In practice RSA keys of this length are never used and X931 padding is very
      rare. Even if someone did use an excessively short RSA key, the chances of
      them combining that with a longer digest and X931 padding is very
      small. For these reasons I do not believe there is a security implication to
      this. Thanks to Kevin Wojtysiak (Int3 Solutions) and Paramjot Oberoi (Int3
      Solutions) for reporting this issue.
      
      Reviewed-by: default avatarAndy Polyakov <appro@openssl.org>
      34166d41