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| author | Denis Efremov <efremov@ispras.ru> | 2019-07-12 21:55:21 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-07-26 09:14:18 +0200 |
| commit | 5b565f3276f3bafdf912e94ede83430aa604ed08 (patch) | |
| tree | 5e53dc3a1a11a0a3cd58cd146f7eb68c91af99ef /drivers/block | |
| parent | 6e34fd07484a0622a17b40e0ca89ed451260ef45 (diff) | |
| download | linux-stable-5b565f3276f3bafdf912e94ede83430aa604ed08.tar.gz linux-stable-5b565f3276f3bafdf912e94ede83430aa604ed08.tar.bz2 linux-stable-5b565f3276f3bafdf912e94ede83430aa604ed08.zip | |
floppy: fix out-of-bounds read in next_valid_format
[ Upstream commit 5635f897ed83fd539df78e98ba69ee91592f9bb8 ]
This fixes a global out-of-bounds read access in the next_valid_format
function of the floppy driver.
The values from autodetect field of the struct floppy_drive_params are
used as indices for the floppy_type array in the next_valid_format
function 'floppy_type[DP->autodetect[probed_format]].sect'.
To trigger the bug, one could use a value out of range and set the drive
parameters with the FDSETDRVPRM ioctl. A floppy disk is not required to
be inserted.
CAP_SYS_ADMIN is required to call FDSETDRVPRM.
The patch adds the check for values of the autodetect 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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/block')
| -rw-r--r-- | drivers/block/floppy.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c index b1425b218606..dd49737effbf 100644 --- a/drivers/block/floppy.c +++ b/drivers/block/floppy.c @@ -3391,6 +3391,20 @@ static int fd_getgeo(struct block_device *bdev, struct hd_geometry *geo) return 0; } +static bool valid_floppy_drive_params(const short autodetect[8]) +{ + size_t floppy_type_size = ARRAY_SIZE(floppy_type); + size_t i = 0; + + for (i = 0; i < 8; ++i) { + if (autodetect[i] < 0 || + autodetect[i] >= floppy_type_size) + return false; + } + + return true; +} + static int fd_locked_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long param) { @@ -3517,6 +3531,8 @@ 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)) + return -EINVAL; *UDP = inparam.dp; break; case FDGETDRVPRM: @@ -3714,6 +3730,8 @@ 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)) + return -EINVAL; mutex_lock(&floppy_mutex); UDP->cmos = v.cmos; UDP->max_dtr = v.max_dtr; |