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| author |   Denis Efremov <efremov@ispras.ru> | 2019-07-12 21:55:21 +0300 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-17 14:45:49 -0700 |
| commit | 5635f897ed83fd539df78e98ba69ee91592f9bb8 (patch) | |
| tree | cc7a5fc94670775c0fb7c8e556c9079b08b9f7cd /drivers | |
| parent | floppy: fix div-by-zero in setup_format_params (diff) | |
| download | linux-dev-5635f897ed83fd539df78e98ba69ee91592f9bb8.tar.xz linux-dev-5635f897ed83fd539df78e98ba69ee91592f9bb8.zip | |
floppy: fix out-of-bounds read in next_valid_format
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>
Diffstat (limited to 'drivers')
| -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 51246bc9709a..b70d6e103a57 100644 --- a/drivers/block/floppy.c +++ b/drivers/block/floppy.c @@ -3380,6 +3380,20 @@ 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) { @@ -3506,6 +3520,8 @@ 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: @@ -3703,6 +3719,8 @@ 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; |