[tip: x86/sgx] selftests/sgx: Fix uninitialized pointer dereferences in encl_get_entry

[tip-bot2 for Jo Van Bulck]

The following commit has been merged into the x86/sgx branch of tip:

Commit-ID:     b84fc2e0139ba4b23b8039bd7cfd242894fe8f8b
Gitweb:        https://git.kernel.org/tip/b84fc2e0139ba4b23b8039bd7cfd242894fe8f8b
Author:        Jo Van Bulck <jo.vanbulck@xxxxxxxxxxxxxx>
AuthorDate:    Thu, 05 Oct 2023 17:38:43 +02:00
Committer:     Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
CommitterDate: Fri, 08 Dec 2023 10:05:26 -08:00

selftests/sgx: Fix uninitialized pointer dereferences in encl_get_entry

Ensure sym_tab and sym_names are zero-initialized and add an early-out
condition in the unlikely (erroneous) case that the enclave ELF file would
not contain a symbol table.

This addresses -Werror=maybe-uninitialized compiler warnings for gcc -O2.

Fixes: 33c5aac3bf32 ("selftests/sgx: Test complete changing of page type flow")
Signed-off-by: Jo Van Bulck <jo.vanbulck@xxxxxxxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
Link: https://lore.kernel.org/all/20231005153854.25566-3-jo.vanbulck%40cs.kuleuven.be
---
 tools/testing/selftests/sgx/load.c |  9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/sgx/load.c b/tools/testing/selftests/sgx/load.c
index 94bdeac..c9f658e 100644
--- a/tools/testing/selftests/sgx/load.c
+++ b/tools/testing/selftests/sgx/load.c
@@ -136,11 +136,11 @@ static bool encl_ioc_add_pages(struct encl *encl, struct encl_segment *seg)
  */
 uint64_t encl_get_entry(struct encl *encl, const char *symbol)
 {
+	Elf64_Sym *symtab = NULL;
+	char *sym_names = NULL;
 	Elf64_Shdr *sections;
-	Elf64_Sym *symtab;
 	Elf64_Ehdr *ehdr;
-	char *sym_names;
-	int num_sym;
+	int num_sym = 0;
 	int i;
 
 	ehdr = encl->bin;
@@ -161,6 +161,9 @@ uint64_t encl_get_entry(struct encl *encl, const char *symbol)
 		}
 	}
 
+	if (!symtab || !sym_names)
+		return 0;
+
 	for (i = 0; i < num_sym; i++) {
 		Elf64_Sym *sym = &symtab[i];