ide-cd: fix oops when using growisofs

cdrom_read_capacity() will blindly return the capacity from the device
without sanity-checking it.  This later causes code in fs/buffer.c to
oops.

Fix this by checking that the device is telling us sensible things.

From: Jens Axboe <jens.axboe@oracle.com>
Cc: Michael Buesch <mb@bu3sch.de>
Cc: Jan Kara <jack@suse.cz>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: <stable@kernel.org>
Cc: Borislav Petkov <petkovbb@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[bart: print device name instead of driver name]
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
[harvey: blocklen is a big-endian value]
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

1 files changed, 22 insertions, 5 deletions

diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
index 8f253e5f26a8..e617cf08aef6 100644
--- a/drivers/ide/ide-cd.c
+++ b/drivers/ide/ide-cd.c
@@ -1311,13 +1311,30 @@ static int cdrom_read_capacity(ide_drive_t *drive, unsigned long *capacity,
 
         stat = ide_cd_queue_pc(drive, cmd, 0, &capbuf, &len, sense, 0,
                                REQ_QUIET);
-        if (stat == 0) {
-                *capacity = 1 + be32_to_cpu(capbuf.lba);
-                *sectors_per_frame =
-                        be32_to_cpu(capbuf.blocklen) >> SECTOR_BITS;
+        if (stat)
+                return stat;
+
+        /*
+         * Sanity check the given block size
+         */
+        switch (capbuf.blocklen) {
+        case __constant_cpu_to_be32(512):
+        case __constant_cpu_to_be32(1024):
+        case __constant_cpu_to_be32(2048):
+        case __constant_cpu_to_be32(4096):
+                break;
+        default:
+                printk(KERN_ERR "%s: weird block size %u\n",
+                        drive->name, capbuf.blocklen);
+                printk(KERN_ERR "%s: default to 2kb block size\n",
+                        drive->name);
+                capbuf.blocklen = __constant_cpu_to_be32(2048);
+                break;
         }
 
-        return stat;
+        *capacity = 1 + be32_to_cpu(capbuf.lba);
+        *sectors_per_frame = be32_to_cpu(capbuf.blocklen) >> SECTOR_BITS;
+        return 0;
 }
 
 static int cdrom_read_tocentry(ide_drive_t *drive, int trackno, int msf_flag,