diff options
| author | Ian Abbott <abbotti@mev.co.uk> | 2025-07-25 15:10:34 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-08-19 12:57:01 +0200 |
| commit | 7afba9221f70d4cbce0f417c558879cba0eb5e66 (patch) | |
| tree | 29da11034d2297d40e4972083ab6f8594c791578 | |
| parent | 3cd212e895ca2d58963fdc6422502b10dd3966bb (diff) | |
comedi: Make insn_rw_emulate_bits() do insn->n samples
The `insn_rw_emulate_bits()` function is used as a default handler for
`INSN_READ` instructions for subdevices that have a handler for
`INSN_BITS` but not for `INSN_READ`. Similarly, it is used as a default
handler for `INSN_WRITE` instructions for subdevices that have a handler
for `INSN_BITS` but not for `INSN_WRITE`. It works by emulating the
`INSN_READ` or `INSN_WRITE` instruction handling with a constructed
`INSN_BITS` instruction. However, `INSN_READ` and `INSN_WRITE`
instructions are supposed to be able read or write multiple samples,
indicated by the `insn->n` value, but `insn_rw_emulate_bits()` currently
only handles a single sample. For `INSN_READ`, the comedi core will
copy `insn->n` samples back to user-space. (That triggered KASAN
kernel-infoleak errors when `insn->n` was greater than 1, but that is
being fixed more generally elsewhere in the comedi core.)
Make `insn_rw_emulate_bits()` either handle `insn->n` samples, or return
an error, to conform to the general expectation for `INSN_READ` and
`INSN_WRITE` handlers.
Fixes: ed9eccbe8970 ("Staging: add comedi core")
Cc: stable <stable@kernel.org> # 5.13+
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://lore.kernel.org/r/20250725141034.87297-1-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/comedi/drivers.c | 23 |
1 files changed, 12 insertions, 11 deletions
diff --git a/drivers/comedi/drivers.c b/drivers/comedi/drivers.c index f1dc854928c1..c9ebaadc5e82 100644 --- a/drivers/comedi/drivers.c +++ b/drivers/comedi/drivers.c @@ -620,11 +620,9 @@ static int insn_rw_emulate_bits(struct comedi_device *dev, unsigned int chan = CR_CHAN(insn->chanspec); unsigned int base_chan = (chan < 32) ? 0 : chan; unsigned int _data[2]; + unsigned int i; int ret; - if (insn->n == 0) - return 0; - memset(_data, 0, sizeof(_data)); memset(&_insn, 0, sizeof(_insn)); _insn.insn = INSN_BITS; @@ -635,18 +633,21 @@ static int insn_rw_emulate_bits(struct comedi_device *dev, if (insn->insn == INSN_WRITE) { if (!(s->subdev_flags & SDF_WRITABLE)) return -EINVAL; - _data[0] = 1U << (chan - base_chan); /* mask */ - _data[1] = data[0] ? (1U << (chan - base_chan)) : 0; /* bits */ + _data[0] = 1U << (chan - base_chan); /* mask */ } + for (i = 0; i < insn->n; i++) { + if (insn->insn == INSN_WRITE) + _data[1] = data[i] ? _data[0] : 0; /* bits */ - ret = s->insn_bits(dev, s, &_insn, _data); - if (ret < 0) - return ret; + ret = s->insn_bits(dev, s, &_insn, _data); + if (ret < 0) + return ret; - if (insn->insn == INSN_READ) - data[0] = (_data[1] >> (chan - base_chan)) & 1; + if (insn->insn == INSN_READ) + data[i] = (_data[1] >> (chan - base_chan)) & 1; + } - return 1; + return insn->n; } static int __comedi_device_postconfig_async(struct comedi_device *dev, |