doc/share/security/patches/SA-06:14/fpu.patch
Bjoern A. Zeeb 3571e53040 Import FreeBSD Security Advisories and Errata Notices, as well as their
patches for easier mirroring, to eliminate a special copy, to make
www.freebsd.org/security a full copy of security.freebsd.org and be
eventually be the same.

For now files are just sitting there.   The symlinks are missing.

Discussed on:	www (repository location)
Discussed with:	simon (so)
2012-08-15 06:19:40 +00:00

141 lines
3.7 KiB
Diff

Index: sys/amd64/amd64/fpu.c
===================================================================
RCS file: /home/ncvs/src/sys/amd64/amd64/fpu.c,v
retrieving revision 1.157
diff -u -I__FBSDID -r1.157 fpu.c
--- sys/amd64/amd64/fpu.c 11 Mar 2005 22:16:09 -0000 1.157
+++ sys/amd64/amd64/fpu.c 16 Apr 2006 20:18:07 -0000
@@ -96,6 +96,8 @@
typedef u_char bool_t;
+static void fpu_clean_state(void);
+
int hw_float = 1;
SYSCTL_INT(_hw,HW_FLOATINGPT, floatingpoint,
CTLFLAG_RD, &hw_float, 0,
@@ -407,6 +409,8 @@
PCPU_SET(fpcurthread, curthread);
pcb = PCPU_GET(curpcb);
+ fpu_clean_state();
+
if ((pcb->pcb_flags & PCB_FPUINITDONE) == 0) {
/*
* This is the first time this thread has used the FPU,
@@ -474,6 +478,7 @@
s = intr_disable();
if (td == PCPU_GET(fpcurthread)) {
+ fpu_clean_state();
fxrstor(addr);
intr_restore(s);
} else {
@@ -484,6 +489,37 @@
}
/*
+ * On AuthenticAMD processors, the fxrstor instruction does not restore
+ * the x87's stored last instruction pointer, last data pointer, and last
+ * opcode values, except in the rare case in which the exception summary
+ * (ES) bit in the x87 status word is set to 1.
+ *
+ * In order to avoid leaking this information across processes, we clean
+ * these values by performing a dummy load before executing fxrstor().
+ */
+static double dummy_variable = 0.0;
+static void
+fpu_clean_state(void)
+{
+ u_short status;
+
+ /*
+ * Clear the ES bit in the x87 status word if it is currently
+ * set, in order to avoid causing a fault in the upcoming load.
+ */
+ fnstsw(&status);
+ if (status & 0x80)
+ fnclex();
+
+ /*
+ * Load the dummy variable into the x87 stack. This mangles
+ * the x87 stack, but we don't care since we're about to call
+ * fxrstor() anyway.
+ */
+ __asm __volatile("ffree %%st(7); fld %0" : : "m" (dummy_variable));
+}
+
+/*
* This really sucks. We want the acpi version only, but it requires
* the isa_if.h file in order to get the definitions.
*/
Index: sys/i386/isa/npx.c
===================================================================
RCS file: /home/ncvs/src/sys/i386/isa/npx.c,v
retrieving revision 1.164
diff -u -I__FBSDID -r1.164 npx.c
--- sys/i386/isa/npx.c 6 Apr 2006 17:17:45 -0000 1.164
+++ sys/i386/isa/npx.c 16 Apr 2006 20:18:08 -0000
@@ -142,6 +142,10 @@
typedef u_char bool_t;
+#ifdef CPU_ENABLE_SSE
+static void fpu_clean_state(void);
+#endif
+
static void fpusave(union savefpu *);
static void fpurstor(union savefpu *);
static int npx_attach(device_t dev);
@@ -952,15 +956,49 @@
fnsave(addr);
}
+#ifdef CPU_ENABLE_SSE
+/*
+ * On AuthenticAMD processors, the fxrstor instruction does not restore
+ * the x87's stored last instruction pointer, last data pointer, and last
+ * opcode values, except in the rare case in which the exception summary
+ * (ES) bit in the x87 status word is set to 1.
+ *
+ * In order to avoid leaking this information across processes, we clean
+ * these values by performing a dummy load before executing fxrstor().
+ */
+static double dummy_variable = 0.0;
+static void
+fpu_clean_state(void)
+{
+ u_short status;
+
+ /*
+ * Clear the ES bit in the x87 status word if it is currently
+ * set, in order to avoid causing a fault in the upcoming load.
+ */
+ fnstsw(&status);
+ if (status & 0x80)
+ fnclex();
+
+ /*
+ * Load the dummy variable into the x87 stack. This mangles
+ * the x87 stack, but we don't care since we're about to call
+ * fxrstor() anyway.
+ */
+ __asm __volatile("ffree %%st(7); fld %0" : : "m" (dummy_variable));
+}
+#endif /* CPU_ENABLE_SSE */
+
static void
fpurstor(addr)
union savefpu *addr;
{
#ifdef CPU_ENABLE_SSE
- if (cpu_fxsr)
+ if (cpu_fxsr) {
+ fpu_clean_state();
fxrstor(addr);
- else
+ } else
#endif
frstor(addr);
}