[PATCH 5.4 125/154] objtool, media: dib8000: Prevent divide-by-zero in dib8000_set_dds()

Greg Kroah-Hartman
2025-04-08T12:07:48Z

From: Josh Poimboeuf <jpoimboe@kernel.org>

[ Upstream commit e63d465f59011dede0a0f1d21718b59a64c3ff5c ]

If dib8000_set_dds()'s call to dib8000_read32() returns zero, the result
is a divide-by-zero. Prevent that from happening.

Fixes the following warning with an UBSAN kernel:

drivers/media/dvb-frontends/dib8000.o: warning: objtool: dib8000_tune() falls through to next function dib8096p_cfg_DibRx()

Fixes: 173a64cb3fcf ("[media] dib8000: enhancement")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/bd1d504d930ae3f073b1e071bcf62cae7708773c.1742852847.git.jpoimboe@kernel.org
Closes: https://lore.kernel.org/r/202503210602.fvH5DO1i-lkp@intel.com/
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/media/dvb-frontends/dib8000.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/media/dvb-frontends/dib8000.c b/drivers/media/dvb-frontends/dib8000.c
index 02cb48223dc67..a28cbbd9e475c 100644
--- a/drivers/media/dvb-frontends/dib8000.c
+++ b/drivers/media/dvb-frontends/dib8000.c
@@ -2701,8 +2701,11 @@ static void dib8000_set_dds(struct dib8000_state *state, s32 offset_khz)
u8 ratio;

if (state->revision == 0x8090) {
+ u32 internal = dib8000_read32(state, 23) / 1000;
+
ratio = 4;
- unit_khz_dds_val = (1<<26) / (dib8000_read32(state, 23) / 1000);
+
+ unit_khz_dds_val = (1<<26) / (internal ?: 1);
if (offset_khz < 0)
dds = (1 << 26) - (abs_offset_khz * unit_khz_dds_val);
else
--
2.39.5