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| author |   Denis Efremov <efremov@ispras.ru> | 2019-07-12 21:55:22 +0300 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-17 14:45:50 -0700 |
| commit | 9b04609b784027968348796a18f601aed9db3789 (patch) | |
| tree | 96a133df881bb20e6bd1b1c58f28abe96a389583 /drivers/block/floppy.c | |
| parent | floppy: fix out-of-bounds read in next_valid_format (diff) | |
| download | linux-dev-9b04609b784027968348796a18f601aed9db3789.tar.xz linux-dev-9b04609b784027968348796a18f601aed9db3789.zip | |
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/floppy.c')
| -rw-r--r-- | drivers/block/floppy.c | 11 |
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; |