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authorAndy Lutomirski <luto@kernel.org>2016-09-30 10:58:58 -0700
committerIngo Molnar <mingo@kernel.org>2016-10-20 09:21:41 +0200
commitd17af5056cf9e9fc05e68832f7c15687fcc12281 (patch)
tree5849ec3001300e88b215f9d4e47e6b2b18e335fa
parentb18cb64ead400c01bf1580eeba330ace51f8087d (diff)
downloadop-kernel-dev-d17af5056cf9e9fc05e68832f7c15687fcc12281.zip
op-kernel-dev-d17af5056cf9e9fc05e68832f7c15687fcc12281.tar.gz
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: Andy Lutomirski <luto@kernel.org> Acked-by: Thomas 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: Ingo Molnar <mingo@kernel.org>
-rw-r--r--include/linux/mm.h2
-rw-r--r--mm/util.c4
-rw-r--r--security/selinux/hooks.c2
3 files changed, 5 insertions, 3 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index e9caec6..a658a51 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -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,
diff --git a/mm/util.c b/mm/util.c
index 662cddf..c174e89 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 0850579..09fd610 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -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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