[S390] Add EX_TABLE for addressing exception in usercopy functions.

This patch adds an EX_TABLE entry to mvc{p|s|os} usercopy functions that
may be called with KERNEL_DS. In combination with collaborative memory
management, kernel pages marked as unused may trigger an adressing exception
in the usercopy functions. This fixes an unhandled addressing exception bug
where strncpy_from_user() is used with len > strnlen and KERNEL_DS, crossing
a page boundary to an unused page.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 14 insertions, 12 deletions

diff --git a/arch/s390/lib/uaccess_mvcos.c b/arch/s390/lib/uaccess_mvcos.c
index 3f15aaf..58da3f4 100644
--- a/arch/s390/lib/uaccess_mvcos.c
+++ b/arch/s390/lib/uaccess_mvcos.c
@@ -36,7 +36,7 @@ static size_t copy_from_user_mvcos(size_t size, const void __user *ptr, void *x)
 	tmp1 = -4096UL;
 	asm volatile(
 		"0: .insn ss,0xc80000000000,0(%0,%2),0(%1),0\n"
-		"   jz    7f\n"
+		"9: jz    7f\n"
 		"1:"ALR"  %0,%3\n"
 		"  "SLR"  %1,%3\n"
 		"  "SLR"  %2,%3\n"
@@ -47,7 +47,7 @@ static size_t copy_from_user_mvcos(size_t size, const void __user *ptr, void *x)
 		"  "CLR"  %0,%4\n"	/* copy crosses next page boundary? */
 		"   jnh   4f\n"
 		"3: .insn ss,0xc80000000000,0(%4,%2),0(%1),0\n"
-		"  "SLR"  %0,%4\n"
+		"10:"SLR"  %0,%4\n"
 		"  "ALR"  %2,%4\n"
 		"4:"LHI"  %4,-1\n"
 		"  "ALR"  %4,%0\n"	/* copy remaining size, subtract 1 */
@@ -61,7 +61,7 @@ static size_t copy_from_user_mvcos(size_t size, const void __user *ptr, void *x)
 		"   j     8f\n"
 		"7:"SLR"  %0,%0\n"
 		"8: \n"
-		EX_TABLE(0b,2b) EX_TABLE(3b,4b)
+		EX_TABLE(0b,2b) EX_TABLE(3b,4b) EX_TABLE(9b,2b) EX_TABLE(10b,4b)
 		: "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
 		: "d" (reg0) : "cc", "memory");
 	return size;
@@ -82,7 +82,7 @@ static size_t copy_to_user_mvcos(size_t size, void __user *ptr, const void *x)
 	tmp1 = -4096UL;
 	asm volatile(
 		"0: .insn ss,0xc80000000000,0(%0,%1),0(%2),0\n"
-		"   jz    4f\n"
+		"6: jz    4f\n"
 		"1:"ALR"  %0,%3\n"
 		"  "SLR"  %1,%3\n"
 		"  "SLR"  %2,%3\n"
@@ -93,11 +93,11 @@ static size_t copy_to_user_mvcos(size_t size, void __user *ptr, const void *x)
 		"  "CLR"  %0,%4\n"	/* copy crosses next page boundary? */
 		"   jnh   5f\n"
 		"3: .insn ss,0xc80000000000,0(%4,%1),0(%2),0\n"
-		"  "SLR"  %0,%4\n"
+		"7:"SLR"  %0,%4\n"
 		"   j     5f\n"
 		"4:"SLR"  %0,%0\n"
 		"5: \n"
-		EX_TABLE(0b,2b) EX_TABLE(3b,5b)
+		EX_TABLE(0b,2b) EX_TABLE(3b,5b) EX_TABLE(6b,2b) EX_TABLE(7b,5b)
 		: "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
 		: "d" (reg0) : "cc", "memory");
 	return size;
diff --git a/arch/s390/lib/uaccess_std.c b/arch/s390/lib/uaccess_std.c
index d2ffbad..07deaee 100644
--- a/arch/s390/lib/uaccess_std.c
+++ b/arch/s390/lib/uaccess_std.c
@@ -36,12 +36,12 @@ size_t copy_from_user_std(size_t size, const void __user *ptr, void *x)
 	tmp1 = -256UL;
 	asm volatile(
 		"0: mvcp  0(%0,%2),0(%1),%3\n"
-		"   jz    8f\n"
+		"10:jz    8f\n"
 		"1:"ALR"  %0,%3\n"
 		"   la    %1,256(%1)\n"
 		"   la    %2,256(%2)\n"
 		"2: mvcp  0(%0,%2),0(%1),%3\n"
-		"   jnz   1b\n"
+		"11:jnz   1b\n"
 		"   j     8f\n"
 		"3: la    %4,255(%1)\n"	/* %4 = ptr + 255 */
 		"  "LHI"  %3,-4096\n"
@@ -50,7 +50,7 @@ size_t copy_from_user_std(size_t size, const void __user *ptr, void *x)
 		"  "CLR"  %0,%4\n"	/* copy crosses next page boundary? */
 		"   jnh   5f\n"
 		"4: mvcp  0(%4,%2),0(%1),%3\n"
-		"  "SLR"  %0,%4\n"
+		"12:"SLR"  %0,%4\n"
 		"  "ALR"  %2,%4\n"
 		"5:"LHI"  %4,-1\n"
 		"  "ALR"  %4,%0\n"	/* copy remaining size, subtract 1 */
@@ -65,6 +65,7 @@ size_t copy_from_user_std(size_t size, const void __user *ptr, void *x)
 		"8:"SLR"  %0,%0\n"
 		"9: \n"
 		EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,5b)
+		EX_TABLE(10b,3b) EX_TABLE(11b,3b) EX_TABLE(12b,5b)
 		: "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
 		: : "cc", "memory");
 	return size;
@@ -85,12 +86,12 @@ size_t copy_to_user_std(size_t size, void __user *ptr, const void *x)
 	tmp1 = -256UL;
 	asm volatile(
 		"0: mvcs  0(%0,%1),0(%2),%3\n"
-		"   jz    5f\n"
+		"7: jz    5f\n"
 		"1:"ALR"  %0,%3\n"
 		"   la    %1,256(%1)\n"
 		"   la    %2,256(%2)\n"
 		"2: mvcs  0(%0,%1),0(%2),%3\n"
-		"   jnz   1b\n"
+		"8: jnz   1b\n"
 		"   j     5f\n"
 		"3: la    %4,255(%1)\n" /* %4 = ptr + 255 */
 		"  "LHI"  %3,-4096\n"
@@ -99,11 +100,12 @@ size_t copy_to_user_std(size_t size, void __user *ptr, const void *x)
 		"  "CLR"  %0,%4\n"	/* copy crosses next page boundary? */
 		"   jnh   6f\n"
 		"4: mvcs  0(%4,%1),0(%2),%3\n"
-		"  "SLR"  %0,%4\n"
+		"9:"SLR"  %0,%4\n"
 		"   j     6f\n"
 		"5:"SLR"  %0,%0\n"
 		"6: \n"
 		EX_TABLE(0b,3b) EX_TABLE(2b,3b) EX_TABLE(4b,6b)
+		EX_TABLE(7b,3b) EX_TABLE(8b,3b) EX_TABLE(9b,6b)
 		: "+a" (size), "+a" (ptr), "+a" (x), "+a" (tmp1), "=a" (tmp2)
 		: : "cc", "memory");
 	return size;