[PATCH 2/3] scsi: Protect against buffer possible overflow in scsi_set_sense_information

Sagi Grimberg
2015-07-12T10:37:02Z

Make sure that the input sense buffer has sufficient length
to fit the information descriptor (12 additional bytes).
Modify scsi_set_sense_information to receive the sense buffer
length and adjust it's callers scsi target and libata.

Reported-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Cc: Tejun Heo <tj@kernel.org>
---
drivers/ata/libata-scsi.c | 4 +++-
drivers/scsi/scsi_common.c | 13 ++++++++++++-
drivers/target/target_core_transport.c | 14 +++++++++++---
include/scsi/scsi_common.h | 2 +-
4 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 3131adc..2fb7c79 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -289,7 +289,9 @@ void ata_scsi_set_sense_information(struct scsi_cmnd *cmd,
return;

information = ata_tf_read_block(tf, NULL);
- scsi_set_sense_information(cmd->sense_buffer, information);
+ scsi_set_sense_information(cmd->sense_buffer,
+ SCSI_SENSE_BUFFERSIZE,
+ information);
}

static ssize_t
diff --git a/drivers/scsi/scsi_common.c b/drivers/scsi/scsi_common.c
index fbf137b..2b27e64 100644
--- a/drivers/scsi/scsi_common.c
+++ b/drivers/scsi/scsi_common.c
@@ -5,6 +5,7 @@
#include <linux/bug.h>
#include <linux/kernel.h>
#include <linux/string.h>
+#include <linux/errno.h>
#include <asm/unaligned.h>
#include <scsi/scsi_common.h>

@@ -249,10 +250,13 @@ EXPORT_SYMBOL(scsi_build_sense_buffer);
* scsi_set_sense_information - set the information field in a
* formatted sense data buffer
* @buf: Where to build sense data
+ * @buf_len: buffer length
* @info: 64-bit information value to be set
*
+ * Return value:
+ * 0 on success or EINVAL for invalid sense buffer length
**/
-void scsi_set_sense_information(u8 *buf, u64 info)
+int scsi_set_sense_information(u8 *buf, int buf_len, u64 info)
{
if ((buf[0] & 0x7f) == 0x72) {
u8 *ucp, len;
@@ -263,6 +267,11 @@ void scsi_set_sense_information(u8 *buf, u64 info)
buf[7] = len + 0xc;
ucp = buf + 8 + len;
}
+
+ if (buf_len < len + 0xc)
+ /* Not enough room for info */
+ return -EINVAL;
+
ucp[0] = 0;
ucp[1] = 0xa;
ucp[2] = 0x80; /* Valid bit */
@@ -272,5 +281,7 @@ void scsi_set_sense_information(u8 *buf, u64 info)
buf[0] |= 0x80;
put_unaligned_be32(info, &buf[3]);
}
+
+ return 0;
}
EXPORT_SYMBOL(scsi_set_sense_information);
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 2bece60..7fb031b 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2729,7 +2729,7 @@ static const struct sense_info sense_info_table[] = {
},
};

-static void translate_sense_reason(struct se_cmd *cmd, sense_reason_t reason)
+static int translate_sense_reason(struct se_cmd *cmd, sense_reason_t reason)
{
const struct sense_info *si;
u8 *buffer = cmd->sense_buffer;
@@ -2756,7 +2756,11 @@ static void translate_sense_reason(struct se_cmd *cmd, sense_reason_t reason)

scsi_build_sense_buffer(0, buffer, si->key, asc, ascq);
if (si->add_sector_info)
- scsi_set_sense_information(buffer, cmd->bad_sector);
+ return scsi_set_sense_information(buffer,
+ cmd->scsi_sense_length,
+ cmd->bad_sector);
+
+ return 0;
}

int
@@ -2774,10 +2778,14 @@ transport_send_check_condition_and_sense(struct se_cmd *cmd,
spin_unlock_irqrestore(&cmd->t_state_lock, flags);

if (!from_transport) {
+ int rc;
+
cmd->se_cmd_flags |= SCF_EMULATED_TASK_SENSE;
- translate_sense_reason(cmd, reason);
cmd->scsi_status = SAM_STAT_CHECK_CONDITION;
cmd->scsi_sense_length = TRANSPORT_SENSE_BUFFER;
+ rc = translate_sense_reason(cmd, reason);
+ if (rc)
+ return rc;
}

trace_target_cmd_complete(cmd);
diff --git a/include/scsi/scsi_common.h b/include/scsi/scsi_common.h
index 156d673..11571b2 100644
--- a/include/scsi/scsi_common.h
+++ b/include/scsi/scsi_common.h
@@ -62,7 +62,7 @@ extern bool scsi_normalize_sense(const u8 *sense_buffer, int sb_len,
struct scsi_sense_hdr *sshdr);

extern void scsi_build_sense_buffer(int desc, u8 *buf, u8 key, u8 asc, u8 ascq);
-extern void scsi_set_sense_information(u8 *buf, u64 info);
+int scsi_set_sense_information(u8 *buf, int buf_len, u64 info);
extern const u8 * scsi_sense_desc_find(const u8 * sense_buffer, int sb_len,
int desc_type);

--
1.8.4.3