From 15fd1dc3dadb4268207fa6797e753541aca09a2a Mon Sep 17 00:00:00 2001
From: Max Filippov <jcmvbkbc@gmail.com>
Date: Thu, 18 Jan 2024 07:06:37 -0800
Subject: [PATCH] fs: binfmt_elf_efpic: don't use missing interpreter's
properties
Static FDPIC executable may get an executable stack even when it has
non-executable GNU_STACK segment. This happens when STACK segment has rw
permissions, but does not specify stack size. In that case FDPIC loader
uses permissions of the interpreter's stack, and for static executables
with no interpreter it results in choosing the arch-default permissions
for the stack.
Fix that by using the interpreter's properties only when the interpreter
is actually used.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Link: https://lore.kernel.org/r/20240118150637.660461-1-jcmvbkbc@gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
---
fs/binfmt_elf_fdpic.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index fefc642541cbe..1920ed69279b5 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -320,7 +320,7 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm)
else
executable_stack = EXSTACK_DEFAULT;
- if (stack_size == 0) {
+ if (stack_size == 0 && interp_params.flags & ELF_FDPIC_FLAG_PRESENT) {
stack_size = interp_params.stack_size;
if (interp_params.flags & ELF_FDPIC_FLAG_EXEC_STACK)
executable_stack = EXSTACK_ENABLE_X;
--
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