| Message ID | 20241026072624.976199-1-quzicheng@huawei.com (mailing list archive) |
|---|---|
| State | New |
| Delegated to: | Neil Armstrong |
| Headers | show |
| Series | clk: meson clk-phase: fix division by zero in meson_clk_degrees_to_val() | expand |
On Sat 26 Oct 2024 at 07:26, Zicheng Qu <quzicheng@huawei.com> wrote: > In the meson_clk_phase_set_phase() function, the variable phase->ph.width > is of type u8, with a range of 0 to 255. When calling Thanks for noticing this. Some remarks though ... > meson_clk_degrees_to_val with width as an argument, if width > 8, > phase_step(width) will return 0. Lead to a division by zero error in > DIV_ROUND_CLOSEST(). The same issue exists in the > meson_clk_triphase_set_phase() and meson_sclk_ws_inv_set_phase(). It would have been worth noting that the issue is hypothetical given that all existing instance of the mentioned drivers have a phase width of 1. > > Fixes: 7b70689b07c1 ("clk: meson: add sclk-ws driver") The "problem" did not appear with this commit. > Cc: <stable@vger.kernel.org> > Signed-off-by: Zicheng Qu <quzicheng@huawei.com> > --- > drivers/clk/meson/clk-phase.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/clk/meson/clk-phase.c b/drivers/clk/meson/clk-phase.c > index c1526fbfb6c4..b88d59b7a90d 100644 > --- a/drivers/clk/meson/clk-phase.c > +++ b/drivers/clk/meson/clk-phase.c > @@ -51,6 +51,9 @@ static int meson_clk_phase_set_phase(struct clk_hw *hw, int degrees) > struct meson_clk_phase_data *phase = meson_clk_phase_data(clk); > unsigned int val; > > + if (phase->ph.width > 8) > + return -EINVAL; > + I don't think erroring out on this condition is correct. A phase encoded on more than 8 bit is valid. I think casting width to 'unsigned int' in phase_step() would be better. > val = meson_clk_degrees_to_val(degrees, phase->ph.width); > meson_parm_write(clk->map, &phase->ph, val); > > @@ -110,6 +113,9 @@ static int meson_clk_triphase_set_phase(struct clk_hw *hw, int degrees) > struct meson_clk_triphase_data *tph = meson_clk_triphase_data(clk); > unsigned int val; > > + if (tph->ph0.width > 8) > + return -EINVAL; > + > val = meson_clk_degrees_to_val(degrees, tph->ph0.width); > meson_parm_write(clk->map, &tph->ph0, val); > meson_parm_write(clk->map, &tph->ph1, val); > @@ -167,6 +173,9 @@ static int meson_sclk_ws_inv_set_phase(struct clk_hw *hw, int degrees) > struct meson_sclk_ws_inv_data *tph = meson_sclk_ws_inv_data(clk); > unsigned int val; > > + if (tph->ph.width > 8) > + return -EINVAL; > + > val = meson_clk_degrees_to_val(degrees, tph->ph.width); > meson_parm_write(clk->map, &tph->ph, val); > meson_parm_write(clk->map, &tph->ws, val ? 0 : 1);
diff --git a/drivers/clk/meson/clk-phase.c b/drivers/clk/meson/clk-phase.c index c1526fbfb6c4..b88d59b7a90d 100644 --- a/drivers/clk/meson/clk-phase.c +++ b/drivers/clk/meson/clk-phase.c @@ -51,6 +51,9 @@ static int meson_clk_phase_set_phase(struct clk_hw *hw, int degrees) struct meson_clk_phase_data *phase = meson_clk_phase_data(clk); unsigned int val; + if (phase->ph.width > 8) + return -EINVAL; + val = meson_clk_degrees_to_val(degrees, phase->ph.width); meson_parm_write(clk->map, &phase->ph, val); @@ -110,6 +113,9 @@ static int meson_clk_triphase_set_phase(struct clk_hw *hw, int degrees) struct meson_clk_triphase_data *tph = meson_clk_triphase_data(clk); unsigned int val; + if (tph->ph0.width > 8) + return -EINVAL; + val = meson_clk_degrees_to_val(degrees, tph->ph0.width); meson_parm_write(clk->map, &tph->ph0, val); meson_parm_write(clk->map, &tph->ph1, val); @@ -167,6 +173,9 @@ static int meson_sclk_ws_inv_set_phase(struct clk_hw *hw, int degrees) struct meson_sclk_ws_inv_data *tph = meson_sclk_ws_inv_data(clk); unsigned int val; + if (tph->ph.width > 8) + return -EINVAL; + val = meson_clk_degrees_to_val(degrees, tph->ph.width); meson_parm_write(clk->map, &tph->ph, val); meson_parm_write(clk->map, &tph->ws, val ? 0 : 1);
In the meson_clk_phase_set_phase() function, the variable phase->ph.width is of type u8, with a range of 0 to 255. When calling meson_clk_degrees_to_val with width as an argument, if width > 8, phase_step(width) will return 0. Lead to a division by zero error in DIV_ROUND_CLOSEST(). The same issue exists in the meson_clk_triphase_set_phase() and meson_sclk_ws_inv_set_phase(). Fixes: 7b70689b07c1 ("clk: meson: add sclk-ws driver") Cc: <stable@vger.kernel.org> Signed-off-by: Zicheng Qu <quzicheng@huawei.com> --- drivers/clk/meson/clk-phase.c | 9 +++++++++ 1 file changed, 9 insertions(+)