The patch below does not apply to the v4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

Thanks, Sasha

------------------ original commit in Linus's tree ------------------

From 6bd301819f8f69331a55ae2336c8b111fc933f3d Mon Sep 17 00:00:00 2001 From: Zicheng Qu quzicheng@huawei.com Date: Tue, 22 Oct 2024 13:43:54 +0000 Subject: [PATCH] staging: iio: frequency: ad9832: fix division by zero in ad9832_calc_freqreg()

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: ea707584bac1 ("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 --- drivers/staging/iio/frequency/ad9832.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/iio/frequency/ad9832.c b/drivers/staging/iio/frequency/ad9832.c index 6c390c4eb26de..492612e8f8bad 100644 --- a/drivers/staging/iio/frequency/ad9832.c +++ b/drivers/staging/iio/frequency/ad9832.c @@ -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) |