| Message ID | 20240917075250.19333-1-amishin@t-argos.ru (mailing list archive) |
|---|---|
| State | Changes Requested, archived |
| Headers | show |
| Series | clk: si5341: Prevent division by zero in si5341_output_clk_determine_rate() | expand |
Quoting Aleksandr Mishin (2024-09-17 00:52:50) > In si5341_output_clk_determine_rate() division by zero is possible if the > following conditions are met: > - rate > (parent_rate / 2); > - (parent_rate / 2) is not multiple of rate; > - CLK_SET_RATE_PARENT flag is not set. > > Add zero value check to prevent division by zero. > > Found by Linux Verification Center (linuxtesting.org) with SVACE. > > Fixes: 61c34af50c5f ("clk: si5341: Switch to determine_rate") Nope. The problem was there before this commit. > Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru> > --- > drivers/clk/clk-si5341.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/clk/clk-si5341.c b/drivers/clk/clk-si5341.c > index 6e8dd7387cfd..d0d68a5bba74 100644 > --- a/drivers/clk/clk-si5341.c > +++ b/drivers/clk/clk-si5341.c > @@ -855,7 +855,7 @@ static int si5341_output_clk_determine_rate(struct clk_hw *hw, > } else { > /* We cannot change our parent's rate, report what we can do */ > r /= rate; > - rate = req->best_parent_rate / (r << 1); > + rate = (r << 1) ? req->best_parent_rate / (r << 1) : 0; This is too ugly. Also, I assume it would be better to provide a higher rate if the rate request allows it. Returning 0 should basically never happen.
diff --git a/drivers/clk/clk-si5341.c b/drivers/clk/clk-si5341.c index 6e8dd7387cfd..d0d68a5bba74 100644 --- a/drivers/clk/clk-si5341.c +++ b/drivers/clk/clk-si5341.c @@ -855,7 +855,7 @@ static int si5341_output_clk_determine_rate(struct clk_hw *hw, } else { /* We cannot change our parent's rate, report what we can do */ r /= rate; - rate = req->best_parent_rate / (r << 1); + rate = (r << 1) ? req->best_parent_rate / (r << 1) : 0; } req->rate = rate;
In si5341_output_clk_determine_rate() division by zero is possible if the following conditions are met: - rate > (parent_rate / 2); - (parent_rate / 2) is not multiple of rate; - CLK_SET_RATE_PARENT flag is not set. Add zero value check to prevent division by zero. Found by Linux Verification Center (linuxtesting.org) with SVACE. Fixes: 61c34af50c5f ("clk: si5341: Switch to determine_rate") Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru> --- drivers/clk/clk-si5341.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)