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authorDenis Efremov <efremov@ispras.ru>2019-07-12 21:55:22 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2019-07-18 00:45:50 +0300
commit9b04609b784027968348796a18f601aed9db3789 (patch)
tree96a133df881bb20e6bd1b1c58f28abe96a389583 /drivers/block
parent5635f897ed83fd539df78e98ba69ee91592f9bb8 (diff)
downloadlinux-9b04609b784027968348796a18f601aed9db3789.tar.xz
floppy: fix invalid pointer dereference in drive_name
This fixes the invalid pointer dereference in the drive_name function of the floppy driver. The native_format field of the struct floppy_drive_params is used as floppy_type array index in the drive_name function. Thus, the field should be checked the same way as the autodetect field. To trigger the bug, one could use a value out of range and set the drive parameters with the FDSETDRVPRM ioctl. Next, FDGETDRVTYP ioctl should be used to call the drive_name. A floppy disk is not required to be inserted. CAP_SYS_ADMIN is required to call FDSETDRVPRM. The patch adds the check for a value of the native_format field to be in the '0 <= x < ARRAY_SIZE(floppy_type)' range of the floppy_type array indices. The bug was found by syzkaller. Signed-off-by: Denis Efremov <efremov@ispras.ru> Tested-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/block')
-rw-r--r--drivers/block/floppy.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
index b70d6e103a57..671a0ae434b4 100644
--- a/drivers/block/floppy.c
+++ b/drivers/block/floppy.c
@@ -3380,7 +3380,8 @@ static int fd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
return 0;
}
-static bool valid_floppy_drive_params(const short autodetect[8])
+static bool valid_floppy_drive_params(const short autodetect[8],
+ int native_format)
{
size_t floppy_type_size = ARRAY_SIZE(floppy_type);
size_t i = 0;
@@ -3391,6 +3392,9 @@ static bool valid_floppy_drive_params(const short autodetect[8])
return false;
}
+ if (native_format < 0 || native_format >= floppy_type_size)
+ return false;
+
return true;
}
@@ -3520,7 +3524,8 @@ static int fd_locked_ioctl(struct block_device *bdev, fmode_t mode, unsigned int
SUPBOUND(size, strlen((const char *)outparam) + 1);
break;
case FDSETDRVPRM:
- if (!valid_floppy_drive_params(inparam.dp.autodetect))
+ if (!valid_floppy_drive_params(inparam.dp.autodetect,
+ inparam.dp.native_format))
return -EINVAL;
*UDP = inparam.dp;
break;
@@ -3719,7 +3724,7 @@ static int compat_setdrvprm(int drive,
return -EPERM;
if (copy_from_user(&v, arg, sizeof(struct compat_floppy_drive_params)))
return -EFAULT;
- if (!valid_floppy_drive_params(v.autodetect))
+ if (!valid_floppy_drive_params(v.autodetect, v.native_format))
return -EINVAL;
mutex_lock(&floppy_mutex);
UDP->cmos = v.cmos;