media: dib8000: avoid division by 0 in dib8000_set_dds()

In dib8000_set_dds(), 1 << 26 (67108864) divided by e.g. 1 apparently can't
fit into 16-bit variable unit_khz_dds_val, being truncated to 0; this will
cause division by 0 while calling dprintk() with debugging enabled (via the
module parameter).  Use s32 instead of s16 to declare the variable, getting
rid of the cast to u16 in the *else* branch as well...

Found by Linux Verification Center (linuxtesting.org) with the Svace static
analysis tool.

Fixes: 173a64cb3fcf ("[media] dib8000: enhancement")
Cc: stable@vger.kernel.org
Signed-off-by: Sergey Shtylyov <s.shtylyov@auroraos.dev>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>

diff --git a/drivers/media/dvb-frontends/dib8000.c b/drivers/media/dvb-frontends/dib8000.c
index ebef27bcc9899070b60481569a99d56389bbea43..d291113291e04909a3017b7205e3286b58f8ca93 100644 (file)
--- a/drivers/media/dvb-frontends/dib8000.c
+++ b/drivers/media/dvb-frontends/dib8000.c
@@ -2695,7 +2695,7 @@ static void dib8000_viterbi_state(struct dib8000_state *state, u8 onoff)
 
 static void dib8000_set_dds(struct dib8000_state *state, s32 offset_khz)
 {
-       s16 unit_khz_dds_val;
+       s32 unit_khz_dds_val;
        u32 abs_offset_khz = abs(offset_khz);
        u32 dds = state->cfg.pll->ifreq & 0x1ffffff;
        u8 invert = !!(state->cfg.pll->ifreq & (1 << 25));
@@ -2716,7 +2716,7 @@ static void dib8000_set_dds(struct dib8000_state *state, s32 offset_khz)
                        dds = (1<<26) - dds;
        } else {
                ratio = 2;
-               unit_khz_dds_val = (u16) (67108864 / state->cfg.pll->internal);
+               unit_khz_dds_val = 67108864 / state->cfg.pll->internal;
 
                if (offset_khz < 0)
                        unit_khz_dds_val *= -1;