pwm: mediatek: Prevent divide-by-zero in pwm_mediatek_config()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: pwm: mediatek: Prevent divide-by-zero in pwm_mediatek_config() With CONFIG_COMPILE_TEST && !CONFIG_HAVE_CLK, pwm_mediatek_config() has a divide-by-zero in the following line: do_div(resolution, clk_get_rate(pc->clk_pwms[pwm->hwpwm])); due to the fact that the !CONFIG_HAVE_CLK version of clk_get_rate() returns zero. This is presumably just a theoretical problem: COMPILE_TEST overrides the dependency on RALINK which would select COMMON_CLK. Regardless it's a good idea to check for the error explicitly to avoid divide-by-zero. Fixes the following warning: drivers/pwm/pwm-mediatek.o: warning: objtool: .text: unexpected end of section [ukleinek: s/CONFIG_CLK/CONFIG_HAVE_CLK/]

References

• https://git.kernel.org/stable/c/8b9f60725d74b72c238e4437c957d0217746b506
• https://git.kernel.org/stable/c/e1206d8e1651c9f62e5640b69b14d925b1a0a00a
• https://git.kernel.org/stable/c/e3cf0c38d3ce754ad63005102fcfeb0b7ff3290b
• https://git.kernel.org/stable/c/f3e9cf266c2c103cf071e15d7a17e2c699fff3c5
• https://git.kernel.org/stable/c/8ddbec73ea2598d8414e8f7103241b55cf877010
• https://git.kernel.org/stable/c/4cb15042b5f3ec0474e91cf379120cc597625dbb
• https://git.kernel.org/stable/c/c343856ff2689ce0afef823592732fc178ef4aac
• https://git.kernel.org/stable/c/77fb96dbe350e8a5ae4965ff9f6e7049f3966a6b
• https://git.kernel.org/stable/c/7ca59947b5fcf94e7ea4029d1bd0f7c41500a161