An initialization vector IV can have any number of bits between 1 and
2^64. So it should be filled to the lower 64-bit in the last step
when computing ghash.
Signed-off-by: openluopworld <wuhanluop@163.com>
diff --git a/ChangeLog.d/bugfix-for-gcm-long-iv-size.txt b/ChangeLog.d/bugfix-for-gcm-long-iv-size.txt
new file mode 100644
index 0000000..c04c4aa
--- /dev/null
+++ b/ChangeLog.d/bugfix-for-gcm-long-iv-size.txt
@@ -0,0 +1,4 @@
+Bugfix
+ * Fix a bug in mbedtls_gcm_starts() when bits of iv are longer than 2^32.
+ * Fix #4884.
+
diff --git a/library/gcm.c b/library/gcm.c
index 948268c..43a5e1b 100644
--- a/library/gcm.c
+++ b/library/gcm.c
@@ -257,6 +257,7 @@
size_t i;
const unsigned char *p;
size_t use_len, olen = 0;
+ uint64_t iv_bits;
GCM_VALIDATE_RET( ctx != NULL );
GCM_VALIDATE_RET( iv != NULL );
@@ -286,7 +287,8 @@
else
{
memset( work_buf, 0x00, 16 );
- MBEDTLS_PUT_UINT32_BE( iv_len * 8, work_buf, 12 );
+ iv_bits = (uint64_t)iv_len * 8;
+ MBEDTLS_PUT_UINT64_BE( iv_bits, work_buf, 8 );
p = iv;
while( iv_len > 0 )