diff --git a/ChangeLog.d/bugfix-2927.txt b/ChangeLog.d/bugfix-2927.txt
new file mode 100644
index 0000000..2213c6e
--- /dev/null
+++ b/ChangeLog.d/bugfix-2927.txt
@@ -0,0 +1,3 @@
+Bugfix
+   * In CTR_DRBG and HMAC_DRBG, don't reset the reseed interval in seed().
+     Fixes #2927.
diff --git a/ChangeLog.d/ecp-bignum-error-checks.txt b/ChangeLog.d/ecp-bignum-error-checks.txt
new file mode 100644
index 0000000..8cad08e
--- /dev/null
+++ b/ChangeLog.d/ecp-bignum-error-checks.txt
@@ -0,0 +1,5 @@
+Bugfix
+   * Fix a memory leak in mbedtls_mpi_sub_abs() when the result was negative
+     (an error condition) and the second operand was aliased to the result.
+   * Fix a case in elliptic curve arithmetic where an out-of-memory condition
+     could go undetected, resulting in an incorrect result.
diff --git a/include/mbedtls/ctr_drbg.h b/include/mbedtls/ctr_drbg.h
index 7aadaf9..24d9870 100644
--- a/include/mbedtls/ctr_drbg.h
+++ b/include/mbedtls/ctr_drbg.h
@@ -200,6 +200,11 @@
  *                      and prepares it for mbedtls_ctr_drbg_seed()
  *                      or mbedtls_ctr_drbg_free().
  *
+ * \note                The reseed interval is
+ *                      #MBEDTLS_CTR_DRBG_RESEED_INTERVAL by default.
+ *                      You can override it by calling
+ *                      mbedtls_ctr_drbg_set_reseed_interval().
+ *
  * \param ctx           The CTR_DRBG context to initialize.
  */
 void mbedtls_ctr_drbg_init( mbedtls_ctr_drbg_context *ctx );
@@ -280,7 +285,8 @@
                    size_t len );
 
 /**
- * \brief               This function clears CTR_CRBG context data.
+ * \brief               This function resets CTR_DRBG context to the state immediately
+ *                      after initial call of mbedtls_ctr_drbg_init().
  *
  * \param ctx           The CTR_DRBG context to clear.
  */
diff --git a/include/mbedtls/hmac_drbg.h b/include/mbedtls/hmac_drbg.h
index 289cf48..cd23a16 100644
--- a/include/mbedtls/hmac_drbg.h
+++ b/include/mbedtls/hmac_drbg.h
@@ -138,6 +138,10 @@
  * This function makes the context ready for mbedtls_hmac_drbg_seed(),
  * mbedtls_hmac_drbg_seed_buf() or mbedtls_hmac_drbg_free().
  *
+ * \note                The reseed interval is #MBEDTLS_HMAC_DRBG_RESEED_INTERVAL
+ *                      by default. Override this value by calling
+ *                      mbedtls_hmac_drbg_set_reseed_interval().
+ *
  * \param ctx           HMAC_DRBG context to be initialized.
  */
 void mbedtls_hmac_drbg_init( mbedtls_hmac_drbg_context *ctx );
@@ -378,7 +382,8 @@
 int mbedtls_hmac_drbg_random( void *p_rng, unsigned char *output, size_t out_len );
 
 /**
- * \brief               Free an HMAC_DRBG context
+ * \brief               This function resets HMAC_DRBG context to the state immediately
+ *                      after initial call of mbedtls_hmac_drbg_init().
  *
  * \param ctx           The HMAC_DRBG context to free.
  */
diff --git a/library/bignum.c b/library/bignum.c
index 0e39e3a..c4eb7b0 100644
--- a/library/bignum.c
+++ b/library/bignum.c
@@ -1201,7 +1201,10 @@
         /* If we ran out of space for the carry, it means that the result
          * is negative. */
         if( n == X->n )
-            return( MBEDTLS_ERR_MPI_NEGATIVE_VALUE );
+        {
+            ret = MBEDTLS_ERR_MPI_NEGATIVE_VALUE;
+            goto cleanup;
+        }
         --X->p[n];
     }
 
diff --git a/library/ctr_drbg.c b/library/ctr_drbg.c
index 184e09f..bc5cc8f 100644
--- a/library/ctr_drbg.c
+++ b/library/ctr_drbg.c
@@ -86,11 +86,17 @@
 {
     memset( ctx, 0, sizeof( mbedtls_ctr_drbg_context ) );
 
+    ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;
+
 #if defined(MBEDTLS_THREADING_C)
     mbedtls_mutex_init( &ctx->mutex );
 #endif
 }
 
+/*
+ *  This function resets CTR_DRBG context to the state immediately
+ *  after initial call of mbedtls_ctr_drbg_init().
+ */
 void mbedtls_ctr_drbg_free( mbedtls_ctr_drbg_context *ctx )
 {
     if( ctx == NULL )
@@ -101,6 +107,10 @@
 #endif
     mbedtls_aes_free( &ctx->aes_ctx );
     mbedtls_zeroize( ctx, sizeof( mbedtls_ctr_drbg_context ) );
+    ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;
+#if defined(MBEDTLS_THREADING_C)
+    mbedtls_mutex_init( &ctx->mutex );
+#endif
 }
 
 void mbedtls_ctr_drbg_set_prediction_resistance( mbedtls_ctr_drbg_context *ctx, int resistance )
@@ -379,7 +389,6 @@
 
     if( ctx->entropy_len == 0 )
         ctx->entropy_len = MBEDTLS_CTR_DRBG_ENTROPY_LEN;
-    ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;
 
     /*
      * Initialize with an empty key
diff --git a/library/ecp_curves.c b/library/ecp_curves.c
index 26f6258..9331587 100644
--- a/library/ecp_curves.c
+++ b/library/ecp_curves.c
@@ -974,7 +974,7 @@
     STORE32; i++;                               \
     cur = c > 0 ? c : 0; STORE32;               \
     cur = 0; while( ++i < MAX32 ) { STORE32; }  \
-    if( c < 0 ) fix_negative( N, c, &C, bits );
+    if( c < 0 ) MBEDTLS_MPI_CHK( fix_negative( N, c, &C, bits ) );
 
 /*
  * If the result is negative, we get it in the form
diff --git a/library/hmac_drbg.c b/library/hmac_drbg.c
index f24a66c..26b15e9 100644
--- a/library/hmac_drbg.c
+++ b/library/hmac_drbg.c
@@ -87,6 +87,8 @@
 {
     memset( ctx, 0, sizeof( mbedtls_hmac_drbg_context ) );
 
+    ctx->reseed_interval = MBEDTLS_HMAC_DRBG_RESEED_INTERVAL;
+
 #if defined(MBEDTLS_THREADING_C)
     mbedtls_mutex_init( &ctx->mutex );
 #endif
@@ -298,8 +300,6 @@
     ctx->f_entropy = f_entropy;
     ctx->p_entropy = p_entropy;
 
-    ctx->reseed_interval = MBEDTLS_HMAC_DRBG_RESEED_INTERVAL;
-
     if( ctx->entropy_len == 0 )
     {
         /*
@@ -444,7 +444,8 @@
 }
 
 /*
- * Free an HMAC_DRBG context
+ *  This function resets HMAC_DRBG context to the state immediately
+ *  after initial call of mbedtls_hmac_drbg_init().
  */
 void mbedtls_hmac_drbg_free( mbedtls_hmac_drbg_context *ctx )
 {
@@ -456,6 +457,10 @@
 #endif
     mbedtls_md_free( &ctx->md_ctx );
     mbedtls_zeroize( ctx, sizeof( mbedtls_hmac_drbg_context ) );
+    ctx->reseed_interval = MBEDTLS_HMAC_DRBG_RESEED_INTERVAL;
+#if defined(MBEDTLS_THREADING_C)
+    mbedtls_mutex_init( &ctx->mutex );
+#endif
 }
 
 #if defined(MBEDTLS_FS_IO)
diff --git a/tests/suites/test_suite_ctr_drbg.function b/tests/suites/test_suite_ctr_drbg.function
index 134ba9c..13669e5 100644
--- a/tests/suites/test_suite_ctr_drbg.function
+++ b/tests/suites/test_suite_ctr_drbg.function
@@ -145,13 +145,16 @@
     memset( out, 0, sizeof( out ) );
     memset( add, 0, sizeof( add ) );
 
+    /* Set reseed interval before seed */
+    mbedtls_ctr_drbg_set_reseed_interval( &ctx, 2 * reps );
+
     /* Init must use entropy */
     last_idx = test_offset_idx;
     TEST_ASSERT( mbedtls_ctr_drbg_seed( &ctx, mbedtls_test_entropy_func, entropy, NULL, 0 ) == 0 );
     TEST_ASSERT( last_idx < test_offset_idx );
 
-    /* By default, PR is off and reseed_interval is large,
-     * so the next few calls should not use entropy */
+    /* By default, PR is off, and reseed interval was set to
+     * 2 * reps so the next few calls should not use entropy */
     last_idx = test_offset_idx;
     for( i = 0; i < reps; i++ )
     {
@@ -167,15 +170,16 @@
     TEST_ASSERT( out[sizeof( out ) - 2] == 0 );
     TEST_ASSERT( out[sizeof( out ) - 1] == 0 );
 
-    /* Set reseed_interval to the number of calls done,
-     * so the next call should reseed */
-    mbedtls_ctr_drbg_set_reseed_interval( &ctx, 2 * reps );
+    /* There have been 2 * reps calls to random. The next call should reseed */
     TEST_ASSERT( mbedtls_ctr_drbg_random( &ctx, out, sizeof( out ) ) == 0 );
     TEST_ASSERT( last_idx < test_offset_idx );
 
-    /* The new few calls should not reseed */
+    /* Set reseed interval after seed */
+    mbedtls_ctr_drbg_set_reseed_interval( &ctx, 4 * reps + 1 );
+
+    /* The next few calls should not reseed */
     last_idx = test_offset_idx;
-    for( i = 0; i < reps / 2; i++ )
+    for( i = 0; i < (2 * reps); i++ )
     {
         TEST_ASSERT( mbedtls_ctr_drbg_random( &ctx, out, sizeof( out ) ) == 0 );
         TEST_ASSERT( mbedtls_ctr_drbg_random_with_add( &ctx, out, sizeof( out ) ,
diff --git a/tests/suites/test_suite_hmac_drbg.function b/tests/suites/test_suite_hmac_drbg.function
index a413f5e..dd8ac9a 100644
--- a/tests/suites/test_suite_hmac_drbg.function
+++ b/tests/suites/test_suite_hmac_drbg.function
@@ -48,14 +48,17 @@
     md_info = mbedtls_md_info_from_type( md_alg );
     TEST_ASSERT( md_info != NULL );
 
+    /* Set reseed interval before seed */
+    mbedtls_hmac_drbg_set_reseed_interval( &ctx, 2 * reps );
+
     /* Init must use entropy */
     last_len = entropy.len;
     TEST_ASSERT( mbedtls_hmac_drbg_seed( &ctx, md_info, mbedtls_test_entropy_func, &entropy,
                                  NULL, 0 ) == 0 );
     TEST_ASSERT( entropy.len < last_len );
 
-    /* By default, PR is off and reseed_interval is large,
-     * so the next few calls should not use entropy */
+    /* By default, PR is off, and reseed interval was set to
+     * 2 * reps so the next few calls should not use entropy */
     last_len = entropy.len;
     for( i = 0; i < reps; i++ )
     {
@@ -71,15 +74,16 @@
     TEST_ASSERT( out[sizeof( out ) - 2] == 0 );
     TEST_ASSERT( out[sizeof( out ) - 1] == 0 );
 
-    /* Set reseed_interval to the number of calls done,
-     * so the next call should reseed */
-    mbedtls_hmac_drbg_set_reseed_interval( &ctx, 2 * reps );
+    /* There have been 2 * reps calls to random. The next call should reseed */
     TEST_ASSERT( mbedtls_hmac_drbg_random( &ctx, out, sizeof( out ) ) == 0 );
     TEST_ASSERT( entropy.len < last_len );
 
+    /* Set reseed interval after seed */
+    mbedtls_hmac_drbg_set_reseed_interval( &ctx, 4 * reps + 1);
+
     /* The new few calls should not reseed */
     last_len = entropy.len;
-    for( i = 0; i < reps / 2; i++ )
+    for( i = 0; i < (2 * reps); i++ )
     {
         TEST_ASSERT( mbedtls_hmac_drbg_random( &ctx, out, sizeof( out ) ) == 0 );
         TEST_ASSERT( mbedtls_hmac_drbg_random_with_add( &ctx, out, sizeof( out ) ,
@@ -200,7 +204,7 @@
     TEST_ASSERT( mbedtls_hmac_drbg_random_with_add( &ctx, my_output, out_len,
                                             add2, add2_len ) == 0 );
 
-    /* clear for second run */
+    /* Reset context for second run */
     mbedtls_hmac_drbg_free( &ctx );
 
     TEST_ASSERT( memcmp( my_output, output, out_len ) == 0 );
diff --git a/tests/suites/test_suite_mpi.data b/tests/suites/test_suite_mpi.data
index a6a6423..a07e9af 100644
--- a/tests/suites/test_suite_mpi.data
+++ b/tests/suites/test_suite_mpi.data
@@ -427,12 +427,6 @@
 Test mbedtls_mpi_add_abs #1
 mbedtls_mpi_add_abs:10:"-643808006803554439230129854961492699151386107534013432918073439524138264842370630061369715394739134090922937332590384720397133335969549256322620979036686633213903952966175107096769180017646161851573147596390153":10:"56125680981752282333498088313568935051383833838594899821664631784577337171193624243181360054669678410455329112434552942717084003541384594864129940145043086760031292483340068923506115878221189886491132772739661669044958531131327771":10:"56125680981752282334141896320372489490613963693556392520816017892111350604111697682705498319512049040516698827829292076808006940873974979584527073481012636016353913462376755556720019831187364993587901952757307830896531678727717924"
 
-Test mbedtls_mpi_add_abs #2 (add to first value)
-mpi_add_abs_add_first:10:"123123":10:"123123":10:"246246"
-
-Test mbedtls_mpi_add_abs #3 (add to second value)
-mpi_add_abs_add_second:10:"123123":10:"123123":10:"246246"
-
 Regression mbedtls_mpi_add_abs (add small to very large MPI with carry rollover)
 mbedtls_mpi_add_abs:16:"FFFFFFFFFFFFFFFFFFFFFFFFFFFFF8":16:"08":16:"1000000000000000000000000000000"
 
diff --git a/tests/suites/test_suite_mpi.function b/tests/suites/test_suite_mpi.function
index d023466..0d311e3 100644
--- a/tests/suites/test_suite_mpi.function
+++ b/tests/suites/test_suite_mpi.function
@@ -570,6 +570,15 @@
     TEST_ASSERT( mbedtls_mpi_add_mpi( &Z, &X, &Y ) == 0 );
     TEST_ASSERT( mbedtls_mpi_cmp_mpi( &Z, &A ) == 0 );
 
+    /* result == first operand */
+    TEST_ASSERT( mbedtls_mpi_add_mpi( &X, &X, &Y ) == 0 );
+    TEST_ASSERT( mbedtls_mpi_cmp_mpi( &X, &A ) == 0 );
+    TEST_ASSERT( mbedtls_mpi_read_string( &X, radix_X, input_X ) == 0 );
+
+    /* result == second operand */
+    TEST_ASSERT( mbedtls_mpi_add_mpi( &Y, &X, &Y ) == 0 );
+    TEST_ASSERT( mbedtls_mpi_cmp_mpi( &Y, &A ) == 0 );
+
 exit:
     mbedtls_mpi_free( &X ); mbedtls_mpi_free( &Y ); mbedtls_mpi_free( &Z ); mbedtls_mpi_free( &A );
 }
@@ -614,44 +623,17 @@
     TEST_ASSERT( mbedtls_mpi_add_abs( &Z, &X, &Y ) == 0 );
     TEST_ASSERT( mbedtls_mpi_cmp_mpi( &Z, &A ) == 0 );
 
-exit:
-    mbedtls_mpi_free( &X ); mbedtls_mpi_free( &Y ); mbedtls_mpi_free( &Z ); mbedtls_mpi_free( &A );
-}
-/* END_CASE */
-
-/* BEGIN_CASE */
-void mpi_add_abs_add_first( int radix_X, char *input_X, int radix_Y,
-                            char *input_Y, int radix_A, char *input_A )
-{
-    mbedtls_mpi X, Y, A;
-    mbedtls_mpi_init( &X ); mbedtls_mpi_init( &Y ); mbedtls_mpi_init( &A );
-
-    TEST_ASSERT( mbedtls_mpi_read_string( &X, radix_X, input_X ) == 0 );
-    TEST_ASSERT( mbedtls_mpi_read_string( &Y, radix_Y, input_Y ) == 0 );
-    TEST_ASSERT( mbedtls_mpi_read_string( &A, radix_A, input_A ) == 0 );
+    /* result == first operand */
     TEST_ASSERT( mbedtls_mpi_add_abs( &X, &X, &Y ) == 0 );
     TEST_ASSERT( mbedtls_mpi_cmp_mpi( &X, &A ) == 0 );
-
-exit:
-    mbedtls_mpi_free( &X ); mbedtls_mpi_free( &Y ); mbedtls_mpi_free( &A );
-}
-/* END_CASE */
-
-/* BEGIN_CASE */
-void mpi_add_abs_add_second( int radix_X, char *input_X, int radix_Y,
-                             char *input_Y, int radix_A, char *input_A )
-{
-    mbedtls_mpi X, Y, A;
-    mbedtls_mpi_init( &X ); mbedtls_mpi_init( &Y ); mbedtls_mpi_init( &A );
-
     TEST_ASSERT( mbedtls_mpi_read_string( &X, radix_X, input_X ) == 0 );
-    TEST_ASSERT( mbedtls_mpi_read_string( &Y, radix_Y, input_Y ) == 0 );
-    TEST_ASSERT( mbedtls_mpi_read_string( &A, radix_A, input_A ) == 0 );
+
+    /* result == second operand */
     TEST_ASSERT( mbedtls_mpi_add_abs( &Y, &X, &Y ) == 0 );
     TEST_ASSERT( mbedtls_mpi_cmp_mpi( &Y, &A ) == 0 );
 
 exit:
-    mbedtls_mpi_free( &X ); mbedtls_mpi_free( &Y ); mbedtls_mpi_free( &A );
+    mbedtls_mpi_free( &X ); mbedtls_mpi_free( &Y ); mbedtls_mpi_free( &Z ); mbedtls_mpi_free( &A );
 }
 /* END_CASE */
 
@@ -685,6 +667,15 @@
     TEST_ASSERT( mbedtls_mpi_sub_mpi( &Z, &X, &Y ) == 0 );
     TEST_ASSERT( mbedtls_mpi_cmp_mpi( &Z, &A ) == 0 );
 
+    /* result == first operand */
+    TEST_ASSERT( mbedtls_mpi_sub_mpi( &X, &X, &Y ) == 0 );
+    TEST_ASSERT( mbedtls_mpi_cmp_mpi( &X, &A ) == 0 );
+    TEST_ASSERT( mbedtls_mpi_read_string( &X, radix_X, input_X ) == 0 );
+
+    /* result == second operand */
+    TEST_ASSERT( mbedtls_mpi_sub_mpi( &Y, &X, &Y ) == 0 );
+    TEST_ASSERT( mbedtls_mpi_cmp_mpi( &Y, &A ) == 0 );
+
 exit:
     mbedtls_mpi_free( &X ); mbedtls_mpi_free( &Y ); mbedtls_mpi_free( &Z ); mbedtls_mpi_free( &A );
 }
@@ -707,6 +698,17 @@
     if( res == 0 )
         TEST_ASSERT( mbedtls_mpi_cmp_mpi( &Z, &A ) == 0 );
 
+    /* result == first operand */
+    TEST_ASSERT( mbedtls_mpi_sub_abs( &X, &X, &Y ) == sub_result );
+    if( sub_result == 0 )
+        TEST_ASSERT( mbedtls_mpi_cmp_mpi( &X, &A ) == 0 );
+    TEST_ASSERT( mbedtls_mpi_read_string( &X, radix_X, input_X ) == 0 );
+
+    /* result == second operand */
+    TEST_ASSERT( mbedtls_mpi_sub_abs( &Y, &X, &Y ) == sub_result );
+    if( sub_result == 0 )
+        TEST_ASSERT( mbedtls_mpi_cmp_mpi( &Y, &A ) == 0 );
+
 exit:
     mbedtls_mpi_free( &X ); mbedtls_mpi_free( &Y ); mbedtls_mpi_free( &Z ); mbedtls_mpi_free( &A );
 }