[PATCH 3/3] mm: Change vm_is_stack_for_task() to vm_is_stack_for_current()
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STALE3641d
From: Andy Lutomirski <hidden>
Date: 2016-09-30 17:59:29
Also in:
lkml
Subsystem:
memory management, memory management - core, selinux security module, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Paul Moore, Stephen Smalley, Linus Torvalds
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: Andy Lutomirski <redacted> --- include/linux/mm.h | 2 +- mm/util.c | 4 +++- security/selinux/hooks.c | 2 +- 3 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ef815b9cd426..c365cf49f54a 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -1403,7 +1403,7 @@ 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,
diff --git a/mm/util.c b/mm/util.c
index 662cddf914af..c174e8921995 100644
--- a/mm/util.c
+++ b/mm/util.c@@ -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)); }
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 13185a6c266a..3a40135bde5e 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c@@ -3505,7 +3505,7 @@ 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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2.7.4