commit 9a3cf3174ddf479ad8c534d04297d153bee753fc
author Gilles Peskine <Gilles.Peskine@arm.com> Wed Jan 27 22:24:30 2021 +0100
committer Gilles Peskine <Gilles.Peskine@arm.com> Mon Feb 01 17:27:04 2021 +0100
tree 3474ac34c2cd3863ce635579989542f6de002af0
parent 5d453ee882a62049ba87891fe7b4b0dc002a5974

Add mpi_sub_abs negative tests with a larger-in-size second operand

Add test cases for mbedtls_mpi_sub_abs() where the second operand has
more limbs than the first operand (which, if the extra limbs are not
all zero, implies that the function returns
MBEDTLS_ERR_MPI_NEGATIVE_VALUE).

This exposes a buffer overflow (reported in #4042).

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

tests/suites/test_suite_mpi.data

diff --git a/tests/suites/test_suite_mpi.data b/tests/suites/test_suite_mpi.data
index 6c520eb..5229253 100644
--- a/tests/suites/test_suite_mpi.data
+++ b/tests/suites/test_suite_mpi.data
@@ -472,18 +472,30 @@
 Test mbedtls_mpi_add_int #2
 mbedtls_mpi_add_int:10:"2039568783564019774057658669290345772801939933143482630947726464532830627227012776329":-9871232:10:"2039568783564019774057658669290345772801939933143482630947726464532830627227002905097"
 
-Base test mbedtls_mpi_sub_abs #1 (Test with larger second input)
+Base test mbedtls_mpi_sub_abs #1 (|B| > |A|)
 mbedtls_mpi_sub_abs:10:"5":10:"7":10:"0":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
 
-Base test mbedtls_mpi_sub_abs #2 (Test with larger second input)
+Base test mbedtls_mpi_sub_abs #2 (|B| > |A|)
 mbedtls_mpi_sub_abs:10:"-5":10:"-7":10:"0":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
 
-Base test mbedtls_mpi_sub_abs #3 (Test with larger second input)
+Base test mbedtls_mpi_sub_abs #3 (|B| > |A|)
 mbedtls_mpi_sub_abs:10:"-5":10:"7":10:"0":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
 
-Base test mbedtls_mpi_sub_abs #4 (Test with larger second input)
+Base test mbedtls_mpi_sub_abs #4 (|B| > |A|)
 mbedtls_mpi_sub_abs:10:"5":10:"-7":10:"0":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
 
+Base test mbedtls_mpi_sub_abs #1 (|B| >> |A| with more limbs)
+mbedtls_mpi_sub_abs:10:"5":16:"123456789abcdef01":10:"0":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
+
+Base test mbedtls_mpi_sub_abs #2 (|B| >> |A| with more limbs)
+mbedtls_mpi_sub_abs:10:"-5":16:"-123456789abcdef01":10:"0":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
+
+Base test mbedtls_mpi_sub_abs #3 (|B| >> |A| with more limbs)
+mbedtls_mpi_sub_abs:10:"-5":16:"123456789abcdef01":10:"0":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
+
+Base test mbedtls_mpi_sub_abs #4 (|B| >> |A| with more limbs)
+mbedtls_mpi_sub_abs:10:"5":16:"-123456789abcdef01":10:"0":MBEDTLS_ERR_MPI_NEGATIVE_VALUE
+
 Base test mbedtls_mpi_sub_abs #1
 mbedtls_mpi_sub_abs:10:"7":10:"5":10:"2":0