[git] GCRYPT - branch, LIBGCRYPT-1-6-BRANCH, updated. libgcrypt-1.6.5-7-ga6855de

[by Werner Koch]

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The branch, LIBGCRYPT-1-6-BRANCH has been updated
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       via  489831a7299b461740f696dabd913eaec03ee16a (commit)
      from  c03cc004133ab261e514ddd37ca40da17df7e6d8 (commit)

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- Log -----------------------------------------------------------------
commit a6855de9fedc16a05f68e3fdda2f6fdaab2388fb
Author: Werner Koch <wk at gnupg.org>
Date:   Wed Mar 23 11:07:52 2016 +0100

    cipher: Check length of supplied tag in _gcry_cipher_gcm_check_tag.
    
    * cipher/cipher-gcm.c (_gcry_cipher_gcm_tag): Check that the provided
    tag length matches the actual tag length.  Avoid gratuitous return
    statements.
    --
    
    Signed-off-by: Werner Koch <wk at gnupg.org>

diff --git a/cipher/cipher-gcm.c b/cipher/cipher-gcm.c
index f7e840d..93d5214 100644
--- a/cipher/cipher-gcm.c
+++ b/cipher/cipher-gcm.c
@@ -1148,13 +1148,18 @@ _gcry_cipher_gcm_tag (gcry_cipher_hd_t c,
 
   if (!check)
     {
+      /* NB: We already checked that OUTBUF is large enough to hold
+         the result.  */
       memcpy (outbuf, c->u_mode.gcm.u_tag.tag, GCRY_GCM_BLOCK_LEN);
-      return GPG_ERR_NO_ERROR;
     }
   else
     {
-      return buf_eq_const(outbuf, c->u_mode.gcm.u_tag.tag, GCRY_GCM_BLOCK_LEN) ?
-               GPG_ERR_NO_ERROR : GPG_ERR_CHECKSUM;
+      /* OUTBUFLEN gives the length of the user supplied tag in OUTBUF
+       * and thus we need to compare its length first.  */
+      if (outbuflen != GCRY_GCM_BLOCK_LEN
+          || !buf_eq_const (outbuf, c->u_mode.gcm.u_tag.tag,
+                            GCRY_GCM_BLOCK_LEN))
+        return GPG_ERR_CHECKSUM;
     }
 
   return 0;

commit 489831a7299b461740f696dabd913eaec03ee16a
Author: Peter Wu <peter at lekensteyn.nl>
Date:   Wed Mar 23 03:45:20 2016 +0100

    Fix buffer overrun in gettag for GCM
    
    * cipher/cipher-gcm.c: copy a fixed length instead of the user-supplied
      number.
    --
    
    The outbuflen is used to check the minimum size, the real tag is always
    of fixed length.
    
    Signed-off-by: Peter Wu <peter at lekensteyn.nl>
    
    Actually this is not a buffer overrun because we copy not more than
    has been allocated for OUTBUF.  However a too long OUTBUFLEN accesses
    data outside of the source buffer.  -wk

diff --git a/cipher/cipher-gcm.c b/cipher/cipher-gcm.c
index 457e337..f7e840d 100644
--- a/cipher/cipher-gcm.c
+++ b/cipher/cipher-gcm.c
@@ -1148,12 +1148,12 @@ _gcry_cipher_gcm_tag (gcry_cipher_hd_t c,
 
   if (!check)
     {
-      memcpy (outbuf, c->u_mode.gcm.u_tag.tag, outbuflen);
+      memcpy (outbuf, c->u_mode.gcm.u_tag.tag, GCRY_GCM_BLOCK_LEN);
       return GPG_ERR_NO_ERROR;
     }
   else
     {
-      return buf_eq_const(outbuf, c->u_mode.gcm.u_tag.tag, outbuflen) ?
+      return buf_eq_const(outbuf, c->u_mode.gcm.u_tag.tag, GCRY_GCM_BLOCK_LEN) ?
                GPG_ERR_NO_ERROR : GPG_ERR_CHECKSUM;
     }
 

-----------------------------------------------------------------------

Summary of changes:
 cipher/cipher-gcm.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)


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