This is a note to let you know that I've just added the patch titled
stable: clamp SUBLEVEL in 4.14
to the 4.14-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:
stable-clamp-sublevel-in-4.14.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 42efb098c75f9d4b95f7cf35d3d52e80cc2fde82 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@xxxxxxxxxx>
Date: Fri, 5 Feb 2021 12:47:02 -0500
Subject: stable: clamp SUBLEVEL in 4.14
From: Sasha Levin <sashal@xxxxxxxxxx>
Right now SUBLEVEL is overflowing, and some userspace may start treating
4.14.256 as 4.15. While out of tree modules have different ways of
extracting the version number (and we're generally ok with breaking
them), we do care about breaking userspace and it would appear that this
overflow might do just that.
Our rules around userspace ABI in the stable kernel are pretty simple:
we don't break it. Thus, while userspace may be checking major/minor, it
shouldn't be doing anything with sublevel.
This patch applies a big band-aid to the 4.14 kernel in the form of
clamping the sublevel to 255.
The clamp is done for the purpose of LINUX_VERSION_CODE only, and
extracting the version number from the Makefile or "make kernelversion"
will continue to work as intended.
We might need to do it later in newer trees, but maybe we'll have a
better solution by then, so I'm ignoring that problem for now.
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/Makefile
+++ b/Makefile
@@ -1162,7 +1162,7 @@ endef
define filechk_version.h
(echo \#define LINUX_VERSION_CODE $(shell \
- expr $(VERSION) \* 65536 + 0$(PATCHLEVEL) \* 256 + 0$(SUBLEVEL)); \
+ expr $(VERSION) \* 65536 + 0$(PATCHLEVEL) \* 256 + 255); \
echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))';)
endef
Patches currently in stable-queue which might be from sashal@xxxxxxxxxx are
queue-4.14/stable-clamp-sublevel-in-4.14.patch
