4.19-stable review patch. If anyone has any objections, please let me know.
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From: Max Filippov jcmvbkbc@gmail.com
[ Upstream commit 15fd1dc3dadb4268207fa6797e753541aca09a2a ]
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 Signed-off-by: Sasha Levin sashal@kernel.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 a7c2efcd0a4a3..0dbbb3a21e6c3 100644 --- a/fs/binfmt_elf_fdpic.c +++ b/fs/binfmt_elf_fdpic.c @@ -324,7 +324,7 @@ 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;