scsi: qedf: Do not touch __user pointer in qedf_dbg_fp_int_cmd_read() directly

The qedf_dbg_fp_int_cmd_read() function invokes sprintf() directly on a
__user pointer, which may crash the kernel.

Avoid doing that by vmalloc()'ating a buffer for scnprintf() and then
calling simple_read_from_buffer() which does a proper copy_to_user() call.

Fixes: 61d8658b4a43 ("scsi: qedf: Add QLogic FastLinQ offload FCoE driver framework.")
Link: https://lore.kernel.org/lkml/20230724120241.40495-1-oleksandr@redhat.com/
Link: https://lore.kernel.org/linux-scsi/20230726101236.11922-1-skashyap@marvell.com/
Cc: Saurav Kashyap <skashyap@marvell.com>
Cc: Rob Evers <revers@redhat.com>
Cc: Johannes Thumshirn <Johannes.Thumshirn@wdc.com>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Jozef Bacik <jobacik@redhat.com>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: GR-QLogic-Storage-Upstream@marvell.com
Cc: linux-scsi@vger.kernel.org
Reviewed-by: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Tested-by: Laurence Oberman <loberman@redhat.com>
Acked-by: Saurav Kashyap <skashyap@marvell.com>
Signed-off-by: Oleksandr Natalenko <oleksandr@redhat.com>
Link: https://lore.kernel.org/r/20230731084034.37021-4-oleksandr@redhat.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/qedf/qedf_dbg.h b/drivers/scsi/qedf/qedf_dbg.h
index f4d81127239ebfd2b8c9d06c09884c9aa4d41cb0..5ec2b817c694a9846c337c88f6e9b59382dbaa1b 100644 (file)
--- a/drivers/scsi/qedf/qedf_dbg.h
+++ b/drivers/scsi/qedf/qedf_dbg.h
@@ -59,6 +59,8 @@ extern uint qedf_debug;
 #define QEDF_LOG_NOTICE        0x40000000      /* Notice logs */
 #define QEDF_LOG_WARN          0x80000000      /* Warning logs */
 
+#define QEDF_DEBUGFS_LOG_LEN (2 * PAGE_SIZE)
+
 /* Debug context structure */
 struct qedf_dbg_ctx {
        unsigned int host_no;

diff --git a/drivers/scsi/qedf/qedf_debugfs.c b/drivers/scsi/qedf/qedf_debugfs.c
index 1c5716540e465b16f417fe60773c5c151bb94b07..451fd236bfd0585f4a7fb86e5c6848f8002b098a 100644 (file)
--- a/drivers/scsi/qedf/qedf_debugfs.c
+++ b/drivers/scsi/qedf/qedf_debugfs.c
@@ -8,6 +8,7 @@
 #include <linux/uaccess.h>
 #include <linux/debugfs.h>
 #include <linux/module.h>
+#include <linux/vmalloc.h>
 
 #include "qedf.h"
 #include "qedf_dbg.h"
@@ -98,7 +99,9 @@ static ssize_t
 qedf_dbg_fp_int_cmd_read(struct file *filp, char __user *buffer, size_t count,
                         loff_t *ppos)
 {
+       ssize_t ret;
        size_t cnt = 0;
+       char *cbuf;
        int id;
        struct qedf_fastpath *fp = NULL;
        struct qedf_dbg_ctx *qedf_dbg =
@@ -108,19 +111,25 @@ qedf_dbg_fp_int_cmd_read(struct file *filp, char __user *buffer, size_t count,
 
        QEDF_INFO(qedf_dbg, QEDF_LOG_DEBUGFS, "entered\n");
 
-       cnt = sprintf(buffer, "\nFastpath I/O completions\n\n");
+       cbuf = vmalloc(QEDF_DEBUGFS_LOG_LEN);
+       if (!cbuf)
+               return 0;
+
+       cnt += scnprintf(cbuf + cnt, QEDF_DEBUGFS_LOG_LEN - cnt, "\nFastpath I/O completions\n\n");
 
        for (id = 0; id < qedf->num_queues; id++) {
                fp = &(qedf->fp_array[id]);
                if (fp->sb_id == QEDF_SB_ID_NULL)
                        continue;
-               cnt += sprintf((buffer + cnt), "#%d: %lu\n", id,
-                              fp->completions);
+               cnt += scnprintf(cbuf + cnt, QEDF_DEBUGFS_LOG_LEN - cnt,
+                                "#%d: %lu\n", id, fp->completions);
        }
 
-       cnt = min_t(int, count, cnt - *ppos);
-       *ppos += cnt;
-       return cnt;
+       ret = simple_read_from_buffer(buffer, count, ppos, cbuf, cnt);
+
+       vfree(cbuf);
+
+       return ret;
 }
 
 static ssize_t