From bfb4a2b95875a47a01234f2de113ec089d524e71 Mon Sep 17 00:00:00 2001 From: Rolf Eike Beer Date: Wed, 19 Oct 2022 09:32:35 +0200 Subject: [PATCH] exec: simplify initial stack size expansion I had a hard time trying to understand completely why it is using vm_end in one side of the expression and vm_start in the other one, and using something in the "if" clause that is not an exact copy of what is used below. The whole point is that the stack_size variable that was used in the "if" clause is the difference between vm_start and vm_end, which is not far away but makes this thing harder to read than it must be. Signed-off-by: Rolf Eike Beer Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/2017429.gqNitNVd0C@mobilepool36.emlix.com --- fs/exec.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index 1644bf10fb9d..9585bc1bc970 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -843,16 +843,13 @@ int setup_arg_pages(struct linux_binprm *bprm, * will align it up. */ rlim_stack = bprm->rlim_stack.rlim_cur & PAGE_MASK; + + stack_expand = min(rlim_stack, stack_size + stack_expand); + #ifdef CONFIG_STACK_GROWSUP - if (stack_size + stack_expand > rlim_stack) - stack_base = vma->vm_start + rlim_stack; - else - stack_base = vma->vm_end + stack_expand; + stack_base = vma->vm_start + stack_expand; #else - if (stack_size + stack_expand > rlim_stack) - stack_base = vma->vm_end - rlim_stack; - else - stack_base = vma->vm_start - stack_expand; + stack_base = vma->vm_end - stack_expand; #endif current->mm->start_stack = bprm->p; ret = expand_stack(vma, stack_base);