On 2/1/22 3:47 PM, Reinette Chatre wrote:
== Background ==
The SGX selftests track parts of the enclave binaries in an array: encl->segment_tbl[]. That array is dynamically allocated early (but not first) in the test's lifetime. The array is referenced at the end of the test in encl_delete().
== Problem ==
encl->segment_tbl[] can be NULL if the test fails before its allocation. That leads to a NULL-pointer-dereference in encl_delete(). This is triggered during early failures of the selftest like if the enclave binary ("test_encl.elf") is deleted.
== Solution ==
"==" usage looks a bit odd in the change log.
Ensure encl->segment_tbl[] is valid before attempting to access its members. The offset with which it is accessed, encl->nr_segments, is initialized before encl->segment_tbl[] and thus considered valid to use after the encl->segment_tbl[] check succeeds.
Fixes: 3200505d4de6 ("selftests/sgx: Create a heap for the test enclave") Signed-off-by: Reinette Chatre reinette.chatre@intel.com
Changes since V1:
Rewrite commit message (Dave).
tools/testing/selftests/sgx/load.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/sgx/load.c b/tools/testing/selftests/sgx/load.c index 9d4322c946e2..006b464c8fc9 100644 --- a/tools/testing/selftests/sgx/load.c +++ b/tools/testing/selftests/sgx/load.c @@ -21,7 +21,7 @@ void encl_delete(struct encl *encl) {
- struct encl_segment *heap_seg = &encl->segment_tbl[encl->nr_segments - 1];
- struct encl_segment *heap_seg;
if (encl->encl_base) munmap((void *)encl->encl_base, encl->encl_size); @@ -32,10 +32,11 @@ void encl_delete(struct encl *encl) if (encl->fd) close(encl->fd);
- munmap(heap_seg->src, heap_seg->size);
- if (encl->segment_tbl)
- if (encl->segment_tbl) {
heap_seg = &encl->segment_tbl[encl->nr_segments - 1];munmap(heap_seg->src, heap_seg->size);- }
memset(encl, 0, sizeof(*encl)); }
The rest looks good to me. I can take this through kselftest tree, if not,
Acked-by: Shuah Khan skhan@linuxfoundation.org
thanks, -- Shuah