[BUG] video: fbdev: sis: possible uninitialized-variable access in SiS_SetCRT2FIFO_300()

Hello,

Our static analysis tool finds a possible uninitialized-variable access in the sis driver in Linux 5.14.0-rc3:

At the beginning of the function SiS_SetCRT2FIFO_300(), the variable modeidindex is not initialized. If the following conditions are false, it remains uninitialized. 5346:    if(!SiS_Pr->CRT1UsesCustomMode) 5438:    if(!SiS_Pr->UseCustomMode)

But it is accessed at: 5466:    colorth = SiS_GetColorDepth(SiS_Pr,CRT2ModeNo,modeidindex) >> 1;

I am not quite sure whether this possible uninitialized-variable access is real and how to fix it if it is real. Any feedback would be appreciated, thanks!

Reported-by: TOTE Robot oslab@tsinghua.edu.cn

Best wishes, Tuo Li