Patch "MIPS: fix truncation in __cmpxchg_small for short values" has been added to the 4.20-stable tree

Patch "MIPS: fix truncation in __cmpxchg_small for short values" has been added to the 4.20-stable tree

[gregkh]

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

    MIPS: fix truncation in __cmpxchg_small for short values

to the 4.20-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:
     mips-fix-truncation-in-__cmpxchg_small-for-short-values.patch
and it can be found in the queue-4.20 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 94ee12b507db8b5876e31c9d6c9d84f556a4b49f Mon Sep 17 00:00:00 2001
From: Michael Clark <michaeljclark@mac.com>
Date: Mon, 11 Feb 2019 17:38:29 +1300
Subject: MIPS: fix truncation in __cmpxchg_small for short values

From: Michael Clark <michaeljclark@mac.com>

commit 94ee12b507db8b5876e31c9d6c9d84f556a4b49f upstream.

__cmpxchg_small erroneously uses u8 for load comparison which can
be either char or short. This patch changes the local variable to
u32 which is sufficiently sized, as the loaded value is already
masked and shifted appropriately. Using an integer size avoids
any unnecessary canonicalization from use of non native widths.

This patch is part of a series that adapts the MIPS small word
atomics code for xchg and cmpxchg on short and char to RISC-V.

Cc: RISC-V Patches <patches@groups.riscv.org>
Cc: Linux RISC-V <linux-riscv@lists.infradead.org>
Cc: Linux MIPS <linux-mips@linux-mips.org>
Signed-off-by: Michael Clark <michaeljclark@mac.com>
[paul.burton@mips.com:
  - Fix varialble typo per Jonas Gorski.
  - Consolidate load variable with other declarations.]
Signed-off-by: Paul Burton <paul.burton@mips.com>
Fixes: 3ba7f44d2b19 ("MIPS: cmpxchg: Implement 1 byte & 2 byte cmpxchg()")
Cc: stable@vger.kernel.org # v4.13+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/mips/kernel/cmpxchg.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/arch/mips/kernel/cmpxchg.c
+++ b/arch/mips/kernel/cmpxchg.c
@@ -54,10 +54,9 @@ unsigned long __xchg_small(volatile void
 unsigned long __cmpxchg_small(volatile void *ptr, unsigned long old,
 			      unsigned long new, unsigned int size)
 {
-	u32 mask, old32, new32, load32;
+	u32 mask, old32, new32, load32, load;
 	volatile u32 *ptr32;
 	unsigned int shift;
-	u8 load;
 
 	/* Check that ptr is naturally aligned */
 	WARN_ON((unsigned long)ptr & (size - 1));


Patches currently in stable-queue which might be from michaeljclark@mac.com are

queue-4.20/mips-fix-truncation-in-__cmpxchg_small-for-short-values.patch

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