Patch "mm: Handle 0 flags in _calc_vm_trans() macro" has been added to the 3.18-stable tree

Patch "mm: Handle 0 flags in _calc_vm_trans() macro" has been added to the 3.18-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    mm: Handle 0 flags in _calc_vm_trans() macro

to the 3.18-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-handle-0-flags-in-_calc_vm_trans-macro.patch
and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Mon Dec 18 15:03:25 CET 2017
From: Jan Kara <jack@suse.cz>
Date: Fri, 3 Nov 2017 12:21:21 +0100
Subject: mm: Handle 0 flags in _calc_vm_trans() macro

From: Jan Kara <jack@suse.cz>


[ Upstream commit 592e254502041f953e84d091eae2c68cba04c10b ]

_calc_vm_trans() does not handle the situation when some of the passed
flags are 0 (which can happen if these VM flags do not make sense for
the architecture). Improve the _calc_vm_trans() macro to return 0 in
such situation. Since all passed flags are constant, this does not add
any runtime overhead.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 include/linux/mman.h |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/include/linux/mman.h
+++ b/include/linux/mman.h
@@ -63,8 +63,9 @@ static inline int arch_validate_prot(uns
  * ("bit1" and "bit2" must be single bits)
  */
 #define _calc_vm_trans(x, bit1, bit2) \
+  ((!(bit1) || !(bit2)) ? 0 : \
   ((bit1) <= (bit2) ? ((x) & (bit1)) * ((bit2) / (bit1)) \
-   : ((x) & (bit1)) / ((bit1) / (bit2)))
+   : ((x) & (bit1)) / ((bit1) / (bit2))))
 
 /*
  * Combine the mmap "prot" argument into "vm_flags" used internally.


Patches currently in stable-queue which might be from jack@suse.cz are

queue-3.18/mm-handle-0-flags-in-_calc_vm_trans-macro.patch
queue-3.18/udf-avoid-overflow-when-session-starts-at-large-offset.patch