This is a note to let you know that I've just added the patch titled
mm: make fixup_user_fault() check the vma access rights too
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-make-fixup_user_fault-check-the-vma-access-rights-too.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1b17844b29ae042576bea588164f2f1e9590a8bc Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Date: Tue, 22 Apr 2014 13:49:40 -0700
Subject: mm: make fixup_user_fault() check the vma access rights too
From: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
commit 1b17844b29ae042576bea588164f2f1e9590a8bc upstream.
fixup_user_fault() is used by the futex code when the direct user access
fails, and the futex code wants it to either map in the page in a usable
form or return an error. It relied on handle_mm_fault() to map the
page, and correctly checked the error return from that, but while that
does map the page, it doesn't actually guarantee that the page will be
mapped with sufficient permissions to be then accessed.
So do the appropriate tests of the vma access rights by hand.
[ Side note: arguably handle_mm_fault() could just do that itself, but
we have traditionally done it in the caller, because some callers -
notably get_user_pages() - have been able to access pages even when
they are mapped with PROT_NONE. Maybe we should re-visit that design
decision, but in the meantime this is the minimal patch. ]
Found by Dave Jones running his trinity tool.
Reported-by: Dave Jones <davej@xxxxxxxxxx>
Acked-by: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 5 +++++
1 file changed, 5 insertions(+)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1929,12 +1929,17 @@ int fixup_user_fault(struct task_struct
unsigned long address, unsigned int fault_flags)
{
struct vm_area_struct *vma;
+ vm_flags_t vm_flags;
int ret;
vma = find_extend_vma(mm, address);
if (!vma || address < vma->vm_start)
return -EFAULT;
+ vm_flags = (fault_flags & FAULT_FLAG_WRITE) ? VM_WRITE : VM_READ;
+ if (!(vm_flags & vma->vm_flags))
+ return -EFAULT;
+
ret = handle_mm_fault(mm, vma, address, fault_flags);
if (ret & VM_FAULT_ERROR) {
if (ret & VM_FAULT_OOM)
Patches currently in stable-queue which might be from torvalds@xxxxxxxxxxxxxxxxxxxx are
queue-3.14/mm-make-fixup_user_fault-check-the-vma-access-rights-too.patch
queue-3.14/futex-add-another-early-deadlock-detection-check.patch
queue-3.14/futex-prevent-attaching-to-kernel-threads.patch
queue-3.14/coredump-fix-va_list-corruption.patch
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