| Message ID | 20240917132201.17513-1-adiupina@astralinux.ru (mailing list archive) |
|---|---|
| State | Changes Requested, archived |
| Headers | show |
| Series | [v3] clk: mvebu: Prevent division by zero in clk_double_div_recalc_rate() | expand |
Quoting Alexandra Diupina (2024-09-17 06:22:01) > get_div() may return zero, so it is necessary to check > before calling DIV_ROUND_UP_ULL(). > > Return value of get_div() depends on reg1, reg2, shift1, shift2 > fields of clk_double_div structure which are filled using the > PERIPH_DOUBLEDIV macro. This macro is called from the > PERIPH_CLK_FULL_DD and PERIPH_CLK_MUX_DD macros (the last 4 arguments). > > It is not known exactly what values can be contained in the registers > at the addresses DIV_SEL0, DIV_SEL1, DIV_SEL2, so the final value of > div can be zero. Print an error message and return 0 in this case. > > Found by Linux Verification Center (linuxtesting.org) with SVACE. > > Fixes: 8ca4746a78ab ("clk: mvebu: Add the peripheral clock driver for Armada 3700") > Signed-off-by: Alexandra Diupina <adiupina@astralinux.ru> > --- > v3: fix indentation > v2: added explanations to the commit message and printing > of an error message when div==0 Please stop sending as replies to previous patches. > drivers/clk/mvebu/armada-37xx-periph.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/clk/mvebu/armada-37xx-periph.c b/drivers/clk/mvebu/armada-37xx-periph.c > index 8701a58a5804..b32c6d4d7ee5 100644 > --- a/drivers/clk/mvebu/armada-37xx-periph.c > +++ b/drivers/clk/mvebu/armada-37xx-periph.c > @@ -343,7 +343,12 @@ static unsigned long clk_double_div_recalc_rate(struct clk_hw *hw, > div = get_div(double_div->reg1, double_div->shift1); > div *= get_div(double_div->reg2, double_div->shift2); > > - return DIV_ROUND_UP_ULL((u64)parent_rate, div); > + if (!div) { > + pr_err("Can't recalculate the rate of clock %s\n", hw->init->name); hw->init is set to NULL after registration (see clk_register() code). If div is 0 what does the hardware do? > + return 0; > + } else { > + return DIV_ROUND_UP_ULL((u64)parent_rate, div); > + } > } >
diff --git a/drivers/clk/mvebu/armada-37xx-periph.c b/drivers/clk/mvebu/armada-37xx-periph.c index 8701a58a5804..b32c6d4d7ee5 100644 --- a/drivers/clk/mvebu/armada-37xx-periph.c +++ b/drivers/clk/mvebu/armada-37xx-periph.c @@ -343,7 +343,12 @@ static unsigned long clk_double_div_recalc_rate(struct clk_hw *hw, div = get_div(double_div->reg1, double_div->shift1); div *= get_div(double_div->reg2, double_div->shift2); - return DIV_ROUND_UP_ULL((u64)parent_rate, div); + if (!div) { + pr_err("Can't recalculate the rate of clock %s\n", hw->init->name); + return 0; + } else { + return DIV_ROUND_UP_ULL((u64)parent_rate, div); + } } static const struct clk_ops clk_double_div_ops = {
get_div() may return zero, so it is necessary to check before calling DIV_ROUND_UP_ULL(). Return value of get_div() depends on reg1, reg2, shift1, shift2 fields of clk_double_div structure which are filled using the PERIPH_DOUBLEDIV macro. This macro is called from the PERIPH_CLK_FULL_DD and PERIPH_CLK_MUX_DD macros (the last 4 arguments). It is not known exactly what values can be contained in the registers at the addresses DIV_SEL0, DIV_SEL1, DIV_SEL2, so the final value of div can be zero. Print an error message and return 0 in this case. Found by Linux Verification Center (linuxtesting.org) with SVACE. Fixes: 8ca4746a78ab ("clk: mvebu: Add the peripheral clock driver for Armada 3700") Signed-off-by: Alexandra Diupina <adiupina@astralinux.ru> --- v3: fix indentation v2: added explanations to the commit message and printing of an error message when div==0 drivers/clk/mvebu/armada-37xx-periph.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)