[PATCH 3.19 059/123] s390/pci: fix possible information leak in mmio syscall

[Greg Kroah-Hartman]

3.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sebastian Ott <sebott@xxxxxxxxxxxxxxxxxx>

commit f0483044c1c96089256cda4cf182eea1ead77fe4 upstream.

Make sure that even in error situations we do not use copy_to_user
on uninitialized kernel memory.

Signed-off-by: Sebastian Ott <sebott@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/s390/pci/pci_mmio.c |   17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

--- a/arch/s390/pci/pci_mmio.c
+++ b/arch/s390/pci/pci_mmio.c
@@ -64,8 +64,7 @@ SYSCALL_DEFINE3(s390_pci_mmio_write, uns
 	if (copy_from_user(buf, user_buffer, length))
 		goto out;
 
-	memcpy_toio(io_addr, buf, length);
-	ret = 0;
+	ret = zpci_memcpy_toio(io_addr, buf, length);
 out:
 	if (buf != local_buf)
 		kfree(buf);
@@ -98,16 +97,16 @@ SYSCALL_DEFINE3(s390_pci_mmio_read, unsi
 		goto out;
 	io_addr = (void *)((pfn << PAGE_SHIFT) | (mmio_addr & ~PAGE_MASK));
 
-	ret = -EFAULT;
-	if ((unsigned long) io_addr < ZPCI_IOMAP_ADDR_BASE)
+	if ((unsigned long) io_addr < ZPCI_IOMAP_ADDR_BASE) {
+		ret = -EFAULT;
 		goto out;
-
-	memcpy_fromio(buf, io_addr, length);
-
-	if (copy_to_user(user_buffer, buf, length))
+	}
+	ret = zpci_memcpy_fromio(buf, io_addr, length);
+	if (ret)
 		goto out;
+	if (copy_to_user(user_buffer, buf, length))
+		ret = -EFAULT;
 
-	ret = 0;
 out:
 	if (buf != local_buf)
 		kfree(buf);


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