diff mbox series

[5.10,156/290] kbuild: clamp SUBLEVEL to 255

Message ID 20210315135547.188981758@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

Greg Kroah-Hartman March 15, 2021, 1:54 p.m. UTC 
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[ Upstream commit 9b82f13e7ef316cdc0a8858f1349f4defce3f9e0 ]

Right now if SUBLEVEL becomes larger than 255 it will overflow into the
territory of PATCHLEVEL, causing havoc in userspace that tests for
specific kernel version.

While userspace code tests for MAJOR and PATCHLEVEL, it doesn't test
SUBLEVEL at any point as ABI changes don't happen in the context of
stable tree.

Thus, to avoid overflows, simply clamp SUBLEVEL to it's maximum value in
the context of LINUX_VERSION_CODE. This does not affect "make
kernelversion" and such.

Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 Makefile | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/Makefile b/Makefile
index 7fdb78b48f55..56d375763b0d 100644
--- a/Makefile
+++ b/Makefile
@@ -1247,9 +1247,15 @@  define filechk_utsrelease.h
 endef
 
 define filechk_version.h
-	echo \#define LINUX_VERSION_CODE $(shell                         \
-	expr $(VERSION) \* 65536 + 0$(PATCHLEVEL) \* 256 + 0$(SUBLEVEL)); \
-	echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))'
+	if [ $(SUBLEVEL) -gt 255 ]; then                                 \
+		echo \#define LINUX_VERSION_CODE $(shell                 \
+		expr $(VERSION) \* 65536 + 0$(PATCHLEVEL) \* 256 + 255); \
+	else                                                             \
+		echo \#define LINUX_VERSION_CODE $(shell                 \
+		expr $(VERSION) \* 65536 + 0$(PATCHLEVEL) \* 256 + $(SUBLEVEL)); \
+	fi;                                                              \
+	echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) +  \
+	((c) > 255 ? 255 : (c)))'
 endef
 
 $(version_h): FORCE