FAILED: Patch "staging: iio: frequency: ad9832: fix division by zero in ad9832_calc_freqreg()" failed to apply to v4.19-stable tree

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 <[email protected]>.

Thanks,
Sasha

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

From 6bd301819f8f69331a55ae2336c8b111fc933f3d Mon Sep 17 00:00:00 2001
From: Zicheng Qu <[email protected]>
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.

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

index 6c390c4eb26de..492612e8f8bad 100644
@@ -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) |

2.43.0