Signed-off-by: Khem Raj <raj.k...@gmail.com>
---
...oration-of-MSA-context-in-non-MSA-kernels.patch | 76 ++++++++++++++++++++++
meta/recipes-kernel/linux/linux-yocto_4.4.bb | 1 +
2 files changed, 77 insertions(+)
create mode 100644
meta/recipes-kernel/linux/linux-yocto/v2-MIPS-Prevent-restoration-of-MSA-context-in-non-MSA-kernels.patch
diff --git
a/meta/recipes-kernel/linux/linux-yocto/v2-MIPS-Prevent-restoration-of-MSA-context-in-non-MSA-kernels.patch
b/meta/recipes-kernel/linux/linux-yocto/v2-MIPS-Prevent-restoration-of-MSA-context-in-non-MSA-kernels.patch
new file mode 100644
index 0000000..8511df6
--- /dev/null
+++
b/meta/recipes-kernel/linux/linux-yocto/v2-MIPS-Prevent-restoration-of-MSA-context-in-non-MSA-kernels.patch
@@ -0,0 +1,76 @@
+From patchwork Thu Apr 21 17:04:53 2016
+Content-Type: text/plain; charset="utf-8"
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+Subject: [v2] MIPS: Prevent "restoration" of MSA context in non-MSA kernels
+From: Paul Burton <paul.bur...@imgtec.com>
+X-Patchwork-Id: 13164
+Message-Id: <1461258293-8863-1-git-send-email-paul.bur...@imgtec.com>
+To: <linux-m...@linux-mips.org>, Ralf Baechle <r...@linux-mips.org>
+Cc: Michal Toman <michal.to...@imgtec.com>,
+ Paul Burton <paul.bur...@imgtec.com>, James Hogan <james.ho...@imgtec.com>,
+ "stable # v4 . 3+" <sta...@vger.kernel.org>
+Date: Thu, 21 Apr 2016 18:04:53 +0100
+
+If a kernel doesn't support MSA context (ie. CONFIG_CPU_HAS_MSA=n) then
+it will only keep 64 bits per FP register in thread context, and the
+calls to set_fpr64 in restore_msa_extcontext will overrun the end of the
+FP register context into the FCSR & MSACSR values. GCC 6.x has become
+smart enough to detect this & complain like so:
+
+ arch/mips/kernel/signal.c: In function 'protected_restore_fp_context':
+ ./arch/mips/include/asm/processor.h:114:17: error: array subscript is
above array bounds [-Werror=array-bounds]
+ fpr->val##width[FPR_IDX(width, idx)] = val; \
+ ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
+ ./arch/mips/include/asm/processor.h:118:1: note: in expansion of macro
'BUILD_FPR_ACCESS'
+ BUILD_FPR_ACCESS(64)
+
+The only way to trigger this code to run would be for a program to set
+up an artificial extended MSA context structure following a sigframe &
+execute sigreturn. Whilst this doesn't allow a program to write to any
+state that it couldn't already, it makes little sense to allow this
+"restoration" of MSA context in a system that doesn't support MSA.
+
+Fix this by killing a program with SIGSYS if it tries something as crazy
+as "restoring" fake MSA context in this way, also fixing the build error
+& allowing for most of restore_msa_extcontext to be optimised out of
+kernels without support for MSA.
+
+Signed-off-by: Paul Burton <paul.bur...@imgtec.com>
+Reported-by: Michal Toman <michal.to...@imgtec.com>
+Fixes: bf82cb30c7e5 ("MIPS: Save MSA extended context around signals")
+Cc: James Hogan <james.ho...@imgtec.com>
+Cc: stable <sta...@vger.kernel.org> # v4.3+
+---
+
+Changes in v2:
+- Prevent potential for malformed errno/signal from
protected_restore_fp_context.
+
+ arch/mips/kernel/signal.c | 7 +++++--
+ 1 file changed, 5 insertions(+), 2 deletions(-)
+
+diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c
+index bf792e2..fc7c1f0 100644
+--- a/arch/mips/kernel/signal.c
++++ b/arch/mips/kernel/signal.c
+@@ -195,6 +195,9 @@ static int restore_msa_extcontext(void __user *buf,
unsigned int size)
+ unsigned int csr;
+ int i, err;
+
++ if (!config_enabled(CONFIG_CPU_HAS_MSA))
++ return SIGSYS;
++
+ if (size != sizeof(*msa))
+ return -EINVAL;
+
+@@ -398,8 +401,8 @@ int protected_restore_fp_context(void __user *sc)
+ }
+
+ fp_done:
+- if (used & USED_EXTCONTEXT)
+- err |= restore_extcontext(sc_to_extcontext(sc));
++ if (!err && (used & USED_EXTCONTEXT))
++ err = restore_extcontext(sc_to_extcontext(sc));
+
+ return err ?: sig;
+ }
diff --git a/meta/recipes-kernel/linux/linux-yocto_4.4.bb
b/meta/recipes-kernel/linux/linux-yocto_4.4.bb
index fbb592a..a55ac93 100644
--- a/meta/recipes-kernel/linux/linux-yocto_4.4.bb
+++ b/meta/recipes-kernel/linux/linux-yocto_4.4.bb
@@ -24,6 +24,7 @@ SRCREV_meta ?= "9ab4787fe2aea2ae0fcc31a5e067eaba19ef64c8"
SRC_URI =
"git://git.yoctoproject.org/linux-yocto-4.4.git;name=machine;branch=${KBRANCH};
\
git://git.yoctoproject.org/yocto-kernel-cache;type=kmeta;name=meta;branch=yocto-4.4;destsuffix=${KMETA}
\
file://0001-powerpc-ptrace-Fix-out-of-bounds-array-access-warnin.patch \
+
file://v2-MIPS-Prevent-restoration-of-MSA-context-in-non-MSA-kernels.patch \
"
LINUX_VERSION ?= "4.4.3"
--
2.8.2
--
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