Messages in this thread Patch in this message | | | From | Remi Pommarel <> | Subject | [PATCH] clk: meson: pll: Fix by 0 division in __pll_params_to_rate() | Date | Sun, 8 Dec 2019 22:22:06 +0100 |
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Some meson pll registers can be initialized with 0 as N value, introducing the following division by 0 when computing rate :
UBSAN: Undefined behaviour in drivers/clk/meson/clk-pll.c:75:9 division by zero CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.4.0-rc3-608075-g86c9af8630e1-dirty #400 Call trace: dump_backtrace+0x0/0x1c0 show_stack+0x14/0x20 dump_stack+0xc4/0x100 ubsan_epilogue+0x14/0x68 __ubsan_handle_divrem_overflow+0x98/0xb8 __pll_params_to_rate+0xdc/0x140 meson_clk_pll_recalc_rate+0x278/0x3a0 __clk_register+0x7c8/0xbb0 devm_clk_hw_register+0x54/0xc0 meson_eeclkc_probe+0xf4/0x1a0 platform_drv_probe+0x54/0xd8 really_probe+0x16c/0x438 driver_probe_device+0xb0/0xf0 device_driver_attach+0x94/0xa0 __driver_attach+0x70/0x108 bus_for_each_dev+0xd8/0x128 driver_attach+0x30/0x40 bus_add_driver+0x1b0/0x2d8 driver_register+0xbc/0x1d0 __platform_driver_register+0x78/0x88 axg_driver_init+0x18/0x20 do_one_initcall+0xc8/0x24c kernel_init_freeable+0x2b0/0x344 kernel_init+0x10/0x128 ret_from_fork+0x10/0x18
This checks if N is null before doing the division.
Fixes: 8289aafa4f36 ("clk: meson: improve pll driver results with frac") Signed-off-by: Remi Pommarel <repk@triplefau.lt> --- drivers/clk/meson/clk-pll.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/drivers/clk/meson/clk-pll.c b/drivers/clk/meson/clk-pll.c index ddb1e5634739..6649659f216a 100644 --- a/drivers/clk/meson/clk-pll.c +++ b/drivers/clk/meson/clk-pll.c @@ -66,6 +66,10 @@ static unsigned long __pll_params_to_rate(unsigned long parent_rate, (1 << pll->frac.width)); } + /* Avoid by zero division */ + if (n == 0) + return 0; + return DIV_ROUND_UP_ULL(rate, n); } -- 2.24.0
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