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@xxxxxxxxx>
---
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);
free(encl->segment_tbl);
+ }
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@xxxxxxxxxxxxxxxxxxx>
thanks,
-- Shuah
