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staging: iio: frequency: ad9832: fix division by zero in ad9832_calc_freqreg()

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In the ad9832_write_frequency() function, clk_get_rate() might return 0.
This can lead to a division by zero when calling ad9832_calc_freqreg().
The check if (fout > (clk_get_rate(st->mclk) / 2)) does not protect
against the case when fout is 0. The ad9832_write_frequency() function
is called from ad9832_write(), and fout is derived from a text buffer,
which can contain any value.

Link: https://lore.kernel.org/all/2024100904-CVE-2024-47663-9bdc@gregkh/
Fixes: ea707584ba ("Staging: IIO: DDS: AD9832 / AD9835 driver")
Cc: stable@vger.kernel.org
Signed-off-by: Zicheng Qu <quzicheng@huawei.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://patch.msgid.link/20241022134354.574614-1-quzicheng@huawei.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Zicheng Qu 2024-10-22 13:43:54 +00:00 committed by Jonathan Cameron
parent 795114e849
commit 6bd301819f
1 changed files with 5 additions and 2 deletions
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7
drivers/staging/iio/frequency/ad9832.c
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@ -129,12 +129,15 @@ static unsigned long ad9832_calc_freqreg(unsigned long mclk, unsigned long fout)
static int ad9832_write_frequency(struct ad9832_state *st,
unsigned int addr, unsigned long fout)
{
unsigned long clk_freq;
unsigned long regval;
if (fout > (clk_get_rate(st->mclk) / 2))
clk_freq = clk_get_rate(st->mclk);
if (!clk_freq || fout > (clk_freq / 2))
return -EINVAL;
regval = ad9832_calc_freqreg(clk_get_rate(st->mclk), fout);
regval = ad9832_calc_freqreg(clk_freq, fout);
st->freq_data[0] = cpu_to_be16((AD9832_CMD_FRE8BITSW << CMD_SHIFT) |
(addr << ADD_SHIFT) |