diff --git a/valgrind-3.12.0-x86-gdt-and-ss.patch b/valgrind-3.12.0-x86-gdt-and-ss.patch
new file mode 100644
index 0000000..fbaf984
--- /dev/null
+++ b/valgrind-3.12.0-x86-gdt-and-ss.patch
@@ -0,0 +1,139 @@
+commit c7bcd1f2ee2d466fb556bfc2b33c5ab039b0898d
+Author: sewardj <sewardj@a5019735-40e9-0310-863c-91ae7b9d1cf9>
+Date: Fri Jan 20 09:58:15 2017 +0000
+
+ x86-linux: Initialize x86 system GDT on first use. Bug 344139 comment 3.
+ Patch from Sebastian Lackner, sebastian@fds-team.de.
+
+
+ git-svn-id: svn://svn.valgrind.org/valgrind/trunk@16204 a5019735-40e9-0310-863c-91ae7b9d1cf9
+
+diff --git a/coregrind/m_syswrap/syswrap-x86-linux.c b/coregrind/m_syswrap/syswrap-x86-linux.c
+index f8c4eb4..2f879d8 100644
+--- a/coregrind/m_syswrap/syswrap-x86-linux.c
++++ b/coregrind/m_syswrap/syswrap-x86-linux.c
+@@ -294,11 +294,37 @@ void translate_to_hw_format ( /* IN */ vki_modify_ldt_t* inn,
+ out->LdtEnt.Words.word2 = entry_2;
+ }
+
+-/* Create a zeroed-out GDT. */
+-static VexGuestX86SegDescr* alloc_zeroed_x86_GDT ( void )
++/* Create initial GDT. */
++static VexGuestX86SegDescr* alloc_system_x86_GDT ( void )
+ {
+ Int nbytes = VEX_GUEST_X86_GDT_NENT * sizeof(VexGuestX86SegDescr);
+- return VG_(calloc)("di.syswrap-x86.azxG.1", nbytes, 1);
++ VexGuestX86SegDescr* gdt = VG_(calloc)("di.syswrap-x86.azxG.1", nbytes, 1);
++ vki_modify_ldt_t info;
++ UShort seg;
++
++ VG_(memset)(&info, 0, sizeof(info));
++ info.entry_number = 0;
++ info.base_addr = 0;
++ info.limit = 0xfffff;
++ info.seg_32bit = 1;
++ info.contents = 0;
++ info.read_exec_only = 0;
++ info.limit_in_pages = 1;
++ info.seg_not_present = 0;
++ info.useable = 0;
++ info.reserved = 0;
++
++ asm volatile("movw %%ds, %0" : : "m" (seg));
++ if (!(seg & 4)) translate_to_hw_format(&info, &gdt[seg >> 3], 0);
++ asm volatile("movw %%ss, %0" : : "m" (seg));
++ if (!(seg & 4)) translate_to_hw_format(&info, &gdt[seg >> 3], 0);
++
++ info.contents = 2;
++
++ asm volatile("movw %%cs, %0" : : "m" (seg));
++ if (!(seg & 4)) translate_to_hw_format(&info, &gdt[seg >> 3], 0);
++
++ return gdt;
+ }
+
+ /* Create a zeroed-out LDT. */
+@@ -505,7 +531,7 @@ SysRes ML_(x86_sys_set_thread_area) ( ThreadId tid, vki_modify_ldt_t* info )
+
+ /* If the thread doesn't have a GDT, allocate it now. */
+ if (!gdt) {
+- gdt = alloc_zeroed_x86_GDT();
++ gdt = alloc_system_x86_GDT();
+ VG_(threads)[tid].arch.vex.guest_GDT = (HWord)gdt;
+ }
+
+@@ -564,7 +590,7 @@ static SysRes sys_get_thread_area ( ThreadId tid, vki_modify_ldt_t* info )
+
+ /* If the thread doesn't have a GDT, allocate it now. */
+ if (!gdt) {
+- gdt = alloc_zeroed_x86_GDT();
++ gdt = alloc_system_x86_GDT();
+ VG_(threads)[tid].arch.vex.guest_GDT = (HWord)gdt;
+ }
+
+@@ -616,7 +642,7 @@ void ML_(x86_setup_LDT_GDT) ( /*OUT*/ ThreadArchState *child,
+ child->vex.guest_GDT = (HWord)NULL;
+
+ if (parent->vex.guest_GDT != (HWord)NULL) {
+- child->vex.guest_GDT = (HWord)alloc_zeroed_x86_GDT();
++ child->vex.guest_GDT = (HWord)alloc_system_x86_GDT();
+ copy_GDT_from_to( (VexGuestX86SegDescr*)parent->vex.guest_GDT,
+ (VexGuestX86SegDescr*)child->vex.guest_GDT );
+ }
+commit 5f4041b376f7465cd108ad4d1696b0b8a603a175
+Author: sewardj <sewardj@8f6e269a-dfd6-0310-a8e1-e2731360e62c>
+Date: Fri Jan 20 10:01:42 2017 +0000
+
+ x86: Recognize the SS segment prefix on x86. Bug 344139 comment 4.
+ Patch from Sebastian Lackner, sebastian@fds-team.de.
+
+
+ git-svn-id: svn://svn.valgrind.org/vex/trunk@3299 8f6e269a-dfd6-0310-a8e1-e2731360e62c
+
+diff --git a/VEX/priv/guest_x86_toIR.c b/VEX/priv/guest_x86_toIR.c
+index de09d3a..234d68e 100644
+--- a/VEX/priv/guest_x86_toIR.c
++++ b/VEX/priv/guest_x86_toIR.c
+@@ -1409,6 +1409,7 @@ const HChar* sorbTxt ( UChar sorb )
+ case 0x26: return "%es:";
+ case 0x64: return "%fs:";
+ case 0x65: return "%gs:";
++ case 0x36: return "%ss:";
+ default: vpanic("sorbTxt(x86,guest)");
+ }
+ }
+@@ -1433,6 +1434,7 @@ IRExpr* handleSegOverride ( UChar sorb, IRExpr* virtual )
+ case 0x26: sreg = R_ES; break;
+ case 0x64: sreg = R_FS; break;
+ case 0x65: sreg = R_GS; break;
++ case 0x36: sreg = R_SS; break;
+ default: vpanic("handleSegOverride(x86,guest)");
+ }
+
+@@ -8101,7 +8103,7 @@ DisResult disInstr_X86_WRK (
+ Int sz = 4;
+
+ /* sorb holds the segment-override-prefix byte, if any. Zero if no
+- prefix has been seen, else one of {0x26, 0x3E, 0x64, 0x65}
++ prefix has been seen, else one of {0x26, 0x36, 0x3E, 0x64, 0x65}
+ indicating the prefix. */
+ UChar sorb = 0;
+
+@@ -8255,6 +8257,7 @@ DisResult disInstr_X86_WRK (
+ case 0x26: /* %ES: */
+ case 0x64: /* %FS: */
+ case 0x65: /* %GS: */
++ case 0x36: /* %SS: */
+ if (sorb != 0)
+ goto decode_failure; /* only one seg override allowed */
+ sorb = pre;
+@@ -8274,9 +8277,6 @@ DisResult disInstr_X86_WRK (
+ }
+ break;
+ }
+- case 0x36: /* %SS: */
+- /* SS override cases are not handled */
+- goto decode_failure;
+ default:
+ goto not_a_prefix;
+ }
diff --git a/valgrind.spec b/valgrind.spec
index 443b9b3..242bc27 100644
--- a/valgrind.spec
+++ b/valgrind.spec
@@ -101,6 +101,11 @@ Patch11: valgrind-3.12.0-exit_group.patch
# KDE#373046 Stacks registered by core are never deregistered
Patch12: valgrind-3.12.0-deregister-stack.patch
+# KDE#344139
+# Initialize x86 system GDT on first use.
+# VEX: Recognize the SS segment prefix on x86.
+Patch13: valgrind-3.12.0-x86-gdt-and-ss.patch
+
%if %{build_multilib}
# Ensure glibc{,-devel} is installed for both multilib arches
BuildRequires: /lib/libc.so.6 /usr/lib/libc.so /lib64/libc.so.6 /usr/lib64/libc.so
@@ -222,6 +227,7 @@ Valgrind User Manual for details.
%patch10 -p1
%patch11 -p1
%patch12 -p1
+%patch13 -p1
%build
# We need to use the software collection compiler and binutils if available.
@@ -422,6 +428,7 @@ echo ===============END TESTING===============
- Add valgrind-3.12.0-quick-fatal-sigs.patch
- Add valgrind-3.12.0-exit_group.patch
- Add valgrind-3.12.0-deregister-stack.patch
+- Add valgrind-3.12.0-x86-gdt-and-ss.patch
* Fri Feb 17 2017 Mark Wielaard <mjw@redhat.com> - 3.12.0-5
- Add valgrind-3.12.0-ppc64-r2.patch (#1424367)