3.18-stable patches

added patches:
	arm64-futex-restore-oldval-initialization-to-work-around-buggy-compilers.patch

diff --git a/queue-3.18/arm64-futex-restore-oldval-initialization-to-work-around-buggy-compilers.patch b/queue-3.18/arm64-futex-restore-oldval-initialization-to-work-around-buggy-compilers.patch
new file mode 100644 (file)
index 0000000..3169d40
--- /dev/null
+++ b/queue-3.18/arm64-futex-restore-oldval-initialization-to-work-around-buggy-compilers.patch
@@ -0,0 +1,52 @@
+From 334d683655a0a4a68792ab1de6b20f4b559b0fcd Mon Sep 17 00:00:00 2001
+From: Nathan Chancellor <natechancellor@gmail.com>
+Date: Wed, 17 Apr 2019 00:21:21 -0700
+Subject: arm64: futex: Restore oldval initialization to work around buggy compilers
+
+From: Nathan Chancellor <natechancellor@gmail.com>
+
+commit ff8acf929014b7f87315588e0daf8597c8aa9d1c upstream.
+
+Commit 045afc24124d ("arm64: futex: Fix FUTEX_WAKE_OP atomic ops with
+non-zero result value") removed oldval's zero initialization in
+arch_futex_atomic_op_inuser because it is not necessary. Unfortunately,
+Android's arm64 GCC 4.9.4 [1] does not agree:
+
+../kernel/futex.c: In function 'do_futex':
+../kernel/futex.c:1658:17: warning: 'oldval' may be used uninitialized
+in this function [-Wmaybe-uninitialized]
+   return oldval == cmparg;
+                 ^
+In file included from ../kernel/futex.c:73:0:
+../arch/arm64/include/asm/futex.h:53:6: note: 'oldval' was declared here
+  int oldval, ret, tmp;
+      ^
+
+GCC fails to follow that when ret is non-zero, futex_atomic_op_inuser
+returns right away, avoiding the uninitialized use that it claims.
+Restoring the zero initialization works around this issue.
+
+[1]: https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/aarch64/aarch64-linux-android-4.9/
+
+Cc: stable@vger.kernel.org
+Fixes: 045afc24124d ("arm64: futex: Fix FUTEX_WAKE_OP atomic ops with non-zero result value")
+Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
+Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/arm64/include/asm/futex.h |    2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/arch/arm64/include/asm/futex.h
++++ b/arch/arm64/include/asm/futex.h
+@@ -50,7 +50,7 @@ futex_atomic_op_inuser(unsigned int enco
+       int cmp = (encoded_op >> 24) & 15;
+       int oparg = (int)(encoded_op << 8) >> 20;
+       int cmparg = (int)(encoded_op << 20) >> 20;
+-      int oldval, ret, tmp;
++      int oldval = 0, ret, tmp;
+ 
+       if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28))
+               oparg = 1U << (oparg & 0x1f);

diff --git a/queue-3.18/series b/queue-3.18/series
index 0a844395440242155ac9bf046a4b7cc6dd0f9e57..898cd22a1a63b20bf322cf4c8b75cb0cbb0e0e71 100644 (file)
--- a/queue-3.18/series
+++ b/queue-3.18/series
@@ -102,3 +102,4 @@ x86-kprobes-verify-stack-frame-on-kretprobe.patch
 kprobes-fix-error-check-when-reusing-optimized-probes.patch
 sched-fair-limit-sched_cfs_period_timer-loop-to-avoi.patch
 device_cgroup-fix-rcu-imbalance-in-error-case.patch
+arm64-futex-restore-oldval-initialization-to-work-around-buggy-compilers.patch