user/sven/linux.git/drivers/block/floppy.c, branch v5.4.90

block/floppy: fix contended case in floppy_queue_rq()

2020-06-17T14:40:38Z

commit 263c61581a38d0a5ad1f5f4a9143b27d68caeffd upstream. Since the switch of floppy driver to blk-mq, the contended (fdc_busy) case in floppy_queue_rq() is not handled correctly. In case we reach floppy_queue_rq() with fdc_busy set (i.e. with the floppy locked due to another request still being in-flight), we put the request on the list of requests and return BLK_STS_OK to the block core, without actually scheduling delayed work / doing further processing of the request. This means that processing of this request is postponed until another request comes and passess uncontended. Which in some cases might actually never happen and we keep waiting indefinitely. The simple testcase is for i in `seq 1 2000`; do echo -en $i '\r'; blkid --info /dev/fd0 2> /dev/null; done run in quemu. That reliably causes blkid eventually indefinitely hanging in __floppy_read_block_0() waiting for completion, as the BIO callback never happens, and no further IO is ever submitted on the (non-existent) floppy device. This was observed reliably on qemu-emulated device. Fix that by not queuing the request in the contended case, and return BLK_STS_RESOURCE instead, so that blk core handles the request rescheduling and let it pass properly non-contended later. Fixes: a9f38e1dec107a ("floppy: convert to blk-mq") Cc: stable@vger.kernel.org Tested-by: Libor Pechacek Signed-off-by: Jiri Kosina Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

floppy: check FDC index for errors before assigning it

2020-02-28T16:22:14Z

commit 2e90ca68b0d2f5548804f22f0dd61145516171e3 upstream. Jordy Zomer reported a KASAN out-of-bounds read in the floppy driver in wait_til_ready(). Which on the face of it can't happen, since as Willy Tarreau points out, the function does no particular memory access. Except through the FDCS macro, which just indexes a static allocation through teh current fdc, which is always checked against N_FDC. Except the checking happens after we've already assigned the value. The floppy driver is a disgrace (a lot of it going back to my original horrd "design"), and has no real maintainer. Nobody has the hardware, and nobody really cares. But it still gets used in virtual environment because it's one of those things that everybody supports. The whole thing should be re-written, or at least parts of it should be seriously cleaned up. The 'current fdc' index, which is used by the FDCS macro, and which is often shadowed by a local 'fdc' variable, is a prime example of how not to write code. But because nobody has the hardware or the motivation, let's just fix up the immediate problem with a nasty band-aid: test the fdc index before actually assigning it to the static 'fdc' variable. Reported-by: Jordy Zomer Cc: Willy Tarreau Cc: Dan Carpenter Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

floppy: fix usercopy direction

2019-08-09T13:41:36Z

As sparse points out, these two copy_from_user() should actually be copy_to_user(). Fixes: 229b53c9bf4e ("take floppy compat ioctls to sodding floppy.c") Cc: stable@vger.kernel.org Acked-by: Alexander Popov Reviewed-by: Mukesh Ojha Signed-off-by: Jann Horn Signed-off-by: Jens Axboe

Merge branch 'floppy'

2019-07-18T15:43:20Z

Merge floppy ioctl verification fixes from Denis Efremov. This also marks the floppy driver as orphaned - it turns out that Jiri no longer has working hardware. Actual working physical floppy hardware is getting hard to find, and while Willy was able to test this, I think the driver can be considered pretty much dead from an actual hardware standpoint. The hardware that is still sold seems to be mainly USB-based, which doesn't use this legacy driver at all. The old floppy disk controller is still emulated in various VM environments, so the driver isn't going away, but let's see if anybody is interested to step up to maintain it. The lack of hardware also likely means that the ioctl range verification fixes are probably mostly relevant to anybody using floppies in a virtual environment. Which is probably also going away in favor of USB storage emulation, but who knows. Will Decon reviewed the patches but I'm not rebasing them just for that, so I'll add a Reviewed-by: Will Deacon here instead. * floppy: MAINTAINERS: mark floppy.c orphaned floppy: fix out-of-bounds read in copy_buffer floppy: fix invalid pointer dereference in drive_name floppy: fix out-of-bounds read in next_valid_format floppy: fix div-by-zero in setup_format_params

floppy: fix out-of-bounds read in copy_buffer

2019-07-17T21:45:50Z

This fixes a global out-of-bounds read access in the copy_buffer function of the floppy driver. The FDDEFPRM ioctl allows one to set the geometry of a disk. The sect and head fields (unsigned int) of the floppy_drive structure are used to compute the max_sector (int) in the make_raw_rw_request function. It is possible to overflow the max_sector. Next, max_sector is passed to the copy_buffer function and used in one of the memcpy calls. An unprivileged user could trigger the bug if the device is accessible, but requires a floppy disk to be inserted. The patch adds the check for the .sect * .head multiplication for not overflowing in the set_geometry function. The bug was found by syzkaller. Signed-off-by: Denis Efremov Tested-by: Willy Tarreau Signed-off-by: Linus Torvalds

floppy: fix invalid pointer dereference in drive_name

2019-07-17T21:45:50Z

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 Tested-by: Willy Tarreau Signed-off-by: Linus Torvalds

floppy: fix out-of-bounds read in next_valid_format

2019-07-17T21:45:49Z

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 Tested-by: Willy Tarreau Signed-off-by: Linus Torvalds

floppy: fix div-by-zero in setup_format_params

2019-07-17T21:45:49Z

This fixes a divide by zero error in the setup_format_params function of the floppy driver. Two consecutive ioctls can trigger the bug: The first one should set the drive geometry with such .sect and .rate values for the F_SECT_PER_TRACK to become zero. Next, the floppy format operation should be called. A floppy disk is not required to be inserted. An unprivileged user could trigger the bug if the device is accessible. The patch checks F_SECT_PER_TRACK for a non-zero value in the set_geometry function. The proper check should involve a reasonable upper limit for the .sect and .rate fields, but it could change the UAPI. The patch also checks F_SECT_PER_TRACK in the setup_format_params, and cancels the formatting operation in case of zero. The bug was found by syzkaller. Signed-off-by: Denis Efremov Tested-by: Willy Tarreau Signed-off-by: Linus Torvalds

docs: blockdev: add it to the admin-guide

2019-07-15T14:03:01Z

The blockdev book basically contains user-faced documentation. Signed-off-by: Mauro Carvalho Chehab

docs: blockdev: convert to ReST

2019-07-15T12:20:26Z

Rename the blockdev documentation files to ReST, add an index for them and adjust in order to produce a nice html output via the Sphinx build system. The drbd sub-directory contains some graphs and data flows. Add those too to the documentation. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab