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From: Petre Rodan <petre.rodan@subdimension.ro>
To: linux-iio@vger.kernel.org,
	linux-kernel@vger.kernel.org
Cc: Petre Rodan <petre.rodan@subdimension.ro>,
	Jonathan Cameron <jic23@kernel.org>,
	Lars-Peter Clausen <lars@metafoo.de>
Subject: [PATCH 0/1] tools: iio: fix iio_generic_buffer
Date: Thu,  4 Jan 2024 12:12:44 +0200
Message-ID: <20240104101253.25896-1-petre.rodan@subdimension.ro>
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While executing tools/iio_generic_buffer i was getting this fault:

beagle /usr/src/linux/tools/iio # ./iio_generic_buffer -a -c 10 -N 0 -T 0
iio device number being used is 0
iio trigger number being used is 0
Auto-channels selected but some channels are already activated in sysfs
Proceeding without activating any channels
/sys/bus/iio/devices/iio:device0 mytmr
Floating point exception

The FPE was generated due to a modulo zero in size_from_channelarray()
(all channels[].bytes were zero because channels[] were never populated).

The root of the cause is the seekdir() function within
build_channel_array().

On my system I can observe a clear difference between these two functions:

    seekdir(dp, 0);
    printf("location = %lu\n", telldir(dp)); // location == 4294967295

    rewinddir(dp);
    printf("location = %lu\n", telldir(dp)); // location == 1

The attached patch fixed the bug for me.

I'm using a BeagleBone Black devboard with an up-to-date stable branch
Gentoo Linux OS on top of it.

CHOST:  armv7a-unknown-linux-gnueabihf
kernel: mainline 6.7.0-rc6
glibc:  2.37-r7:2.2::gentoo  USE="caps gd multiarch ssp static-libs -audit
    -cet -compile-locales -crypt -custom-cflags -doc -hash-sysv-compat
    -headers-only -multilib -multilib-bootstrap -nscd -perl -profile
    (-selinux) -stack-realign -suid -systemd -systemtap -test -vanilla"
    (+ contains Gentoo specific patches)

Fixes: <e58537ccce733> ("staging: iio: update example application.")
Signed-off-by: Petre Rodan <petre.rodan@subdimension.ro>

Petre Rodan (1):
  tools: iio: fix iio_generic_buffer

 tools/iio/iio_utils.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--
2.41.0