openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 73 insertions, 0 deletions

diff --git a/drivers/scsi/sd_dif.c b/drivers/scsi/sd_dif.c
new file mode 100644
index 000000000..ff4217fef
--- /dev/null
+++ b/drivers/scsi/sd_dif.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * sd_dif.c - SCSI Data Integrity Field
+ *
+ * Copyright (C) 2007, 2008 Oracle Corporation
+ * Written by: Martin K. Petersen <martin.petersen@oracle.com>
+ */
+
+#include <linux/blk-integrity.h>
+#include <linux/t10-pi.h>
+
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_dbg.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_driver.h>
+#include <scsi/scsi_eh.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi_ioctl.h>
+#include <scsi/scsicam.h>
+
+#include "sd.h"
+
+/*
+ * Configure exchange of protection information between OS and HBA.
+ */
+void sd_dif_config_host(struct scsi_disk *sdkp, struct queue_limits *lim)
+{
+	struct scsi_device *sdp = sdkp->device;
+	u8 type = sdkp->protection_type;
+	struct blk_integrity *bi = &lim->integrity;
+	int dif, dix;
+
+	memset(bi, 0, sizeof(*bi));
+
+	dif = scsi_host_dif_capable(sdp->host, type);
+	dix = scsi_host_dix_capable(sdp->host, type);
+
+	if (!dix && scsi_host_dix_capable(sdp->host, 0)) {
+		dif = 0; dix = 1;
+	}
+
+	if (!dix)
+		return;
+
+	/* Enable DMA of protection information */
+	if (scsi_host_get_guard(sdkp->device->host) & SHOST_DIX_GUARD_IP)
+		bi->csum_type = BLK_INTEGRITY_CSUM_IP;
+	else
+		bi->csum_type = BLK_INTEGRITY_CSUM_CRC;
+
+	if (type != T10_PI_TYPE3_PROTECTION)
+		bi->flags |= BLK_INTEGRITY_REF_TAG;
+
+	bi->metadata_size = sizeof(struct t10_pi_tuple);
+	bi->pi_tuple_size = bi->metadata_size;
+
+	if (dif && type) {
+		bi->flags |= BLK_INTEGRITY_DEVICE_CAPABLE;
+
+		if (!sdkp->ATO)
+			return;
+
+		if (type == T10_PI_TYPE3_PROTECTION)
+			bi->tag_size = sizeof(u16) + sizeof(u32);
+		else
+			bi->tag_size = sizeof(u16);
+	}
+
+	sd_first_printk(KERN_NOTICE, sdkp,
+			"Enabling DIX %s, application tag size %u bytes\n",
+			blk_integrity_profile_name(bi), bi->tag_size);
+}