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commit 10d9aa40ccd25d45a0779cf7625dc8fa0e634176
parent 4f88960c502baa8f13064845bf66394429f35afb
Author: Christian Grothoff <christian@grothoff.org>
Date:   Thu, 13 Aug 2026 20:03:35 +0200

batch size sanity bounds

Diffstat:
M
src/util/crypto_helper_rsa.c
 | 
18
++++++++++++++++++
M
src/util/secmod_rsa.c
 | 
5
++++-

2 files changed, 22 insertions(+), 1 deletion(-)
diff --git a/src/util/crypto_helper_rsa.c b/src/util/crypto_helper_rsa.c
@@ -422,6 +422,22 @@ TALER_CRYPTO_helper_rsa_batch_sign (
   memset (bss,
           0,
           sizeof (*bss) * rsrs_length);
+  /* Every request must fit into an IPC message of its own, together
+     with the batch header; otherwise it could never be transmitted. */
+  for (unsigned int i = 0; i<rsrs_length; i++)
+  {
+    if (rsrs[i].msg_size >=
+        UINT16_MAX
+        - sizeof (struct TALER_CRYPTO_BatchSignRequest)
+        - sizeof (struct TALER_CRYPTO_SignRequest))
+    {
+      GNUNET_break_op (0);
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                  "Message to sign is too large (%llu bytes)\n",
+                  (unsigned long long) rsrs[i].msg_size);
+      return TALER_EC_GENERIC_PARAMETER_MALFORMED;
+    }
+  }
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "Starting signature process\n");
   if (GNUNET_OK !=
@@ -441,6 +457,8 @@ TALER_CRYPTO_helper_rsa_batch_sign (
   {
     unsigned int mlen = sizeof (struct TALER_CRYPTO_BatchSignRequest);
 
+    /* as each individual request fits, this loop always advances rend
+       at least once, and thus the outer loop makes progress */
     while ( (rend < rsrs_length) &&
             (mlen
              + sizeof (struct TALER_CRYPTO_SignRequest)
diff --git a/src/util/secmod_rsa.c b/src/util/secmod_rsa.c
@@ -769,7 +769,10 @@ handle_batch_sign_request (struct TES_Client *client,
   unsigned int idx = 0;
   bool failure = false;
 
-  if (bs > TALER_MAX_COINS)
+  /* an empty batch would be answered with no message at all,
+     leaving the client waiting for a reply forever */
+  if ( (0 == bs) ||
+       (bs > TALER_MAX_COINS) )
   {
     GNUNET_break_op (0);
     return GNUNET_SYSERR;