Commit d17af505 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Ingo Molnar
Browse files

mm: Change vm_is_stack_for_task() to vm_is_stack_for_current()



Asking for a non-current task's stack can't be done without races
unless the task is frozen in kernel mode.  As far as I know,
vm_is_stack_for_task() never had a safe non-current use case.

The __unused annotation is because some KSTK_ESP implementations
ignore their parameter, which IMO is further justification for this
patch.
Signed-off-by: default avatarAndy Lutomirski <luto@kernel.org>
Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Jann Horn <jann@thejh.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux API <linux-api@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tycho Andersen <tycho.andersen@canonical.com>
Link: http://lkml.kernel.org/r/4c3f68f426e6c061ca98b4fc7ef85ffbb0a25b0c.1475257877.git.luto@kernel.org

Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent b18cb64e
......@@ -1391,7 +1391,7 @@ static inline int stack_guard_page_end(struct vm_area_struct *vma,
!vma_growsup(vma->vm_next, addr);
}
int vma_is_stack_for_task(struct vm_area_struct *vma, struct task_struct *t);
int vma_is_stack_for_current(struct vm_area_struct *vma);
extern unsigned long move_page_tables(struct vm_area_struct *vma,
unsigned long old_addr, struct vm_area_struct *new_vma,
......
......@@ -230,8 +230,10 @@ void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
}
/* Check if the vma is being used as a stack by this task */
int vma_is_stack_for_task(struct vm_area_struct *vma, struct task_struct *t)
int vma_is_stack_for_current(struct vm_area_struct *vma)
{
struct task_struct * __maybe_unused t = current;
return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t));
}
......
......@@ -3557,7 +3557,7 @@ static int selinux_file_mprotect(struct vm_area_struct *vma,
} else if (!vma->vm_file &&
((vma->vm_start <= vma->vm_mm->start_stack &&
vma->vm_end >= vma->vm_mm->start_stack) ||
vma_is_stack_for_task(vma, current))) {
vma_is_stack_for_current(vma))) {
rc = current_has_perm(current, PROCESS__EXECSTACK);
} else if (vma->vm_file && vma->anon_vma) {
/*
......
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