From 2d03861e0d1d1ee81efc59338101cdd86a7474f6 Mon Sep 17 00:00:00 2001 From: Reinette Chatre Date: Tue, 8 Feb 2022 13:48:39 -0800 Subject: [PATCH] selftests/sgx: Fix NULL-pointer-dereference upon early test failure == 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 == 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 Signed-off-by: Dave Hansen Acked-by: Shuah Khan Link: https://lkml.kernel.org/r/90a31dfd640ea756fa324712e7cbab4a90fa7518.1644355600.git.reinette.chatre@intel.com --- 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 9d4322c946e2b..006b464c8fc94 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)); } -- 2.30.2