The dt2815 driver crashes when attached to I/O ports without actual
hardware present. This occurs because syzkaller or users can attach
the driver to arbitrary I/O addresses via COMEDI_DEVCONFIG ioctl.

When no hardware exists at the specified port, inb() operations return
0xff (floating bus), but outb() operations can trigger page faults due
to undefined behavior, especially under race conditions:

  BUG: unable to handle page fault for address: 000000007fffff90
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  RIP: 0010:dt2815_attach+0x6e0/0x1110

Add hardware detection by reading the status register before attempting
any write operations. If the read returns 0xff, assume no hardware is
present and fail the attach with -ENODEV. This prevents crashes from
outb() operations on non-existent hardware.

Reported-by: syzbot+72f94b474d6e50b71ffc@syzkaller.appspotmail.com
Cc: stable <stable@kernel.org>
Closes: https://syzkaller.appspot.com/bug?extid=72f94b474d6e50b71ffc
Tested-by: syzbot+72f94b474d6e50b71ffc@syzkaller.appspotmail.com
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
Link: [https://lore.kernel.org/all/20260126070458.10974-1-kartikey406@gmail.com/T/]
Link: [https://lore.kernel.org/all/20260126070458.10974-1-kartikey406@gmail.com/T/
Link: https://patch.msgid.link/20260309104859.503529-1-kartikey406@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

syzbot reported a memory leak [1], because commit 4e1da516debb ("comedi:
Add reference counting for Comedi command handling") did not consider
the exceptional exit case in do_cmd_ioctl() where runflags is not set.
This caused chanlist not to be properly freed by do_become_nonbusy(),
as it only frees chanlist when runflags is correctly set.

Added a check in do_become_nonbusy() for the case where runflags is not
set, to properly free the chanlist memory.

[1]
BUG: memory leak
  backtrace (crc 844a0efa):
    __comedi_get_user_chanlist drivers/comedi/comedi_fops.c:1815 [inline]
    do_cmd_ioctl.part.0+0x112/0x350 drivers/comedi/comedi_fops.c:1890
    do_cmd_ioctl drivers/comedi/comedi_fops.c:1858 [inline]

Fixes: 4e1da516debb ("comedi: Add reference counting for Comedi command handling")
Reported-by: syzbot+f238baf6ded841b5a82e@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=f238baf6ded841b5a82e
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Cc: stable <stable@kernel.org> # 6.19
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://patch.msgid.link/20260310111104.70959-1-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

`struct comedi_device` is the main controlling structure for a COMEDI
device created by the COMEDI subsystem.  It contains a member `spinlock`
containing a spin-lock that is initialized by the COMEDI subsystem, but
is reserved for use by a low-level driver attached to the COMEDI device
(at least since commit 25436dc9d84f ("Staging: comedi: remove RT
code")).

Some COMEDI devices (those created on initialization of the COMEDI
subsystem when the "comedi.comedi_num_legacy_minors" parameter is
non-zero) can be attached to different low-level drivers over their
lifetime using the `COMEDI_DEVCONFIG` ioctl command.  This can result in
inconsistent lock states being reported when there is a mismatch in the
spin-lock locking levels used by each low-level driver to which the
COMEDI device has been attached.  Fix it by reinitializing
`dev->spinlock` before calling the low-level driver's `attach` function
pointer if `CONFIG_LOCKDEP` is enabled.

Reported-by: syzbot+cc9f7f4a7df09f53c4a4@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=cc9f7f4a7df09f53c4a4
Fixes: ed9eccbe8970 ("Staging: add comedi core")
Cc: stable <stable@kernel.org>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://patch.msgid.link/20260225132427.86578-1-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

`me2600_xilinx_download()` loads the firmware that was requested by
`request_firmware()`.  It is possible for it to overrun the source
buffer because it blindly trusts the file format.  It reads a data
stream length from the first 4 bytes into variable `file_length` and
reads the data stream contents of length `file_length` from offset 16
onwards.  Although it checks that the supplied firmware is at least 16
bytes long, it does not check that it is long enough to contain the data
stream.

Add a test to ensure that the supplied firmware is long enough to
contain the header and the data stream.  On failure, log an error and
return `-EINVAL`.

Fixes: 85acac61096f9 ("Staging: comedi: add me_daq driver")
Cc: stable <stable@kernel.org>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://patch.msgid.link/20260205140130.76697-1-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

`me4000_xilinx_download()` loads the firmware that was requested by
`request_firmware()`.  It is possible for it to overrun the source
buffer because it blindly trusts the file format.  It reads a data
stream length from the first 4 bytes into variable `file_length` and
reads the data stream contents of length `file_length` from offset 16
onwards.

Add a test to ensure that the supplied firmware is long enough to
contain the header and the data stream.  On failure, log an error and
return `-EINVAL`.

Note: The firmware loading was totally broken before commit ac584af59945
("staging: comedi: me4000: fix firmware downloading"), but that is the
most sensible target for this fix.

Fixes: ac584af59945 ("staging: comedi: me4000: fix firmware downloading")
Cc: stable <stable@kernel.org>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://patch.msgid.link/20260205133949.71722-1-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

If the driver's COMEDI "attach" handler function (`atmio16d_attach()`)
returns an error, the COMEDI core will call the driver's "detach"
handler function (`atmio16d_detach()`) to clean up.  This calls
`reset_atmio16d()` unconditionally, but depending on where the error
occurred in the attach handler, the device may not have been
sufficiently initialized to call `reset_atmio16d()`.  It uses
`dev->iobase` as the I/O port base address and `dev->private` as the
pointer to the COMEDI device's private data structure.  `dev->iobase`
may still be set to its initial value of 0, which would result in
undesired writes to low I/O port addresses.  `dev->private` may still be
`NULL`, which would result in null pointer dereferences.

Fix `atmio16d_detach()` by checking that `dev->private` is valid
(non-null) before calling `reset_atmio16d()`.  This implies that
`dev->iobase` was set correctly since that is set up before
`dev->private`.

Fixes: 2323b276308a ("Staging: comedi: add ni_at_atmio16d driver")
Cc: stable <stable@kernel.org>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://patch.msgid.link/20260128150011.5006-1-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Conversion performed via this Coccinelle script:

  // SPDX-License-Identifier: GPL-2.0-only
  // Options: --include-headers-for-types --all-includes --include-headers --keep-comments
  virtual patch

  @gfp depends on patch && !(file in "tools") && !(file in "samples")@
  identifier ALLOC = {kmalloc_obj,kmalloc_objs,kmalloc_flex,
 		    kzalloc_obj,kzalloc_objs,kzalloc_flex,
		    kvmalloc_obj,kvmalloc_objs,kvmalloc_flex,
		    kvzalloc_obj,kvzalloc_objs,kvzalloc_flex};
  @@

  	ALLOC(...
  -		, GFP_KERNEL
  	)

  $ make coccicheck MODE=patch COCCI=gfp.cocci

Build and boot tested x86_64 with Fedora 42's GCC and Clang:

Linux version 6.19.0+ (user@host) (gcc (GCC) 15.2.1 20260123 (Red Hat 15.2.1-7), GNU ld version 2.44-12.fc42) #1 SMP PREEMPT_DYNAMIC 1970-01-01
Linux version 6.19.0+ (user@host) (clang version 20.1.8 (Fedora 20.1.8-4.fc42), LLD 20.1.8) #1 SMP PREEMPT_DYNAMIC 1970-01-01

Signed-off-by: Kees Cook <kees@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This converts some of the visually simpler cases that have been split
over multiple lines.  I only did the ones that are easy to verify the
resulting diff by having just that final GFP_KERNEL argument on the next
line.

Somebody should probably do a proper coccinelle script for this, but for
me the trivial script actually resulted in an assertion failure in the
middle of the script.  I probably had made it a bit _too_ trivial.

So after fighting that far a while I decided to just do some of the
syntactically simpler cases with variations of the previous 'sed'
scripts.

The more syntactically complex multi-line cases would mostly really want
whitespace cleanup anyway.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This was done entirely with mindless brute force, using

    git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
        xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'

to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.

Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.

For the same reason the 'flex' versions will be done as a separate
conversion.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:

Single allocations:	kmalloc(sizeof(TYPE), ...)
are replaced with:	kmalloc_obj(TYPE, ...)

Array allocations:	kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with:	kmalloc_objs(TYPE, COUNT, ...)

Flex array allocations:	kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with:	kmalloc_flex(*PTR, FAM, COUNT, ...)

(where TYPE may also be *VAR)

The resulting allocations no longer return "void *", instead returning
"TYPE *".

Signed-off-by: Kees Cook <kees@kernel.org>