USB: usb-storage: Prevent divide-by-0 error in isd200_ata_command

The isd200 sub-driver in usb-storage uses the HEADS and SECTORS values
in the ATA ID information to calculate cylinder and head values when
creating a CDB for READ or WRITE commands.  The calculation involves
division and modulus operations, which will cause a crash if either of
these values is 0.  While this never happens with a genuine device, it
could happen with a flawed or subversive emulation, as reported by the
syzbot fuzzer.

Protect against this possibility by refusing to bind to the device if
either the ATA_ID_HEADS or ATA_ID_SECTORS value in the device's ID
information is 0.  This requires isd200_Initialization() to return a
negative error code when initialization fails; currently it always
returns 0 (even when there is an error).

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-and-tested-by: syzbot+28748250ab47a8f04100@syzkaller.appspotmail.com
Link: https://lore.kernel.org/linux-usb/0000000000003eb868061245ba7f@google.com/
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Reviewed-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/b1e605ea-333f-4ac0-9511-da04f411763e@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/storage/isd200.c b/drivers/usb/storage/isd200.c
index 4e0eef1440b7fd7407cf2158adad796b516aeda5..300aeef160e75c9d84fbd4b69b3c3ad35a774f5b 100644 (file)
--- a/drivers/usb/storage/isd200.c
+++ b/drivers/usb/storage/isd200.c
@@ -1105,7 +1105,7 @@ static void isd200_dump_driveid(struct us_data *us, u16 *id)
 static int isd200_get_inquiry_data( struct us_data *us )
 {
        struct isd200_info *info = (struct isd200_info *)us->extra;
-       int retStatus = ISD200_GOOD;
+       int retStatus;
        u16 *id = info->id;
 
        usb_stor_dbg(us, "Entering isd200_get_inquiry_data\n");
@@ -1137,6 +1137,13 @@ static int isd200_get_inquiry_data( struct us_data *us )
                                isd200_fix_driveid(id);
                                isd200_dump_driveid(us, id);
 
+                               /* Prevent division by 0 in isd200_scsi_to_ata() */
+                               if (id[ATA_ID_HEADS] == 0 || id[ATA_ID_SECTORS] == 0) {
+                                       usb_stor_dbg(us, "   Invalid ATA Identify data\n");
+                                       retStatus = ISD200_ERROR;
+                                       goto Done;
+                               }
+
                                memset(&info->InquiryData, 0, sizeof(info->InquiryData));
 
                                /* Standard IDE interface only supports disks */
@@ -1202,6 +1209,7 @@ static int isd200_get_inquiry_data( struct us_data *us )
                }
        }
 
+ Done:
        usb_stor_dbg(us, "Leaving isd200_get_inquiry_data %08X\n", retStatus);
 
        return(retStatus);
@@ -1481,22 +1489,27 @@ static int isd200_init_info(struct us_data *us)
 
 static int isd200_Initialization(struct us_data *us)
 {
+       int rc = 0;
+
        usb_stor_dbg(us, "ISD200 Initialization...\n");
 
        /* Initialize ISD200 info struct */
 
-       if (isd200_init_info(us) == ISD200_ERROR) {
+       if (isd200_init_info(us) < 0) {
                usb_stor_dbg(us, "ERROR Initializing ISD200 Info struct\n");
+               rc = -ENOMEM;
        } else {
                /* Get device specific data */
 
-               if (isd200_get_inquiry_data(us) != ISD200_GOOD)
+               if (isd200_get_inquiry_data(us) != ISD200_GOOD) {
                        usb_stor_dbg(us, "ISD200 Initialization Failure\n");
-               else
+                       rc = -EINVAL;
+               } else {
                        usb_stor_dbg(us, "ISD200 Initialization complete\n");
+               }
        }
 
-       return 0;
+       return rc;
 }