video: fbdev: sis: fix null ptr dereference

[ Upstream commit ad6f93e9cd56f0b10e9b22e3e137d17a1a035242 ]

Clang static analysis reports this representative error

init.c:2501:18: warning: Array access (from variable 'queuedata') results
  in a null pointer dereference
      templ |= ((queuedata[i] & 0xc0) << 3);

This is the problem block of code

   if(ModeNo > 0x13) {
      ...
      if(SiS_Pr->ChipType == SIS_730) {
	 queuedata = &FQBQData730[0];
      } else {
	 queuedata = &FQBQData[0];
      }
   } else {

   }

queuedata is not set in the else block

Reviewing the old code, the arrays FQBQData730 and FQBQData were
used directly.

So hoist the setting of queuedata out of the if-else block.

Fixes: 544393fe584d ("[PATCH] sisfb update")
Signed-off-by: Tom Rix <trix@redhat.com>
Cc: Thomas Winischhofer <thomas@winischhofer.net>
Cc: Andrew Morton <akpm@osdl.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200805145208.17727-1-trix@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/video/fbdev/sis/init.c b/drivers/video/fbdev/sis/init.c
index dfe3eb769638bd29dd76231f0cbc6f41f9b61566..fde27feae5d0c29bfd581939e66a475ddcc515e4 100644 (file)
--- a/drivers/video/fbdev/sis/init.c
+++ b/drivers/video/fbdev/sis/init.c
@@ -2428,6 +2428,11 @@ SiS_SetCRT1FIFO_630(struct SiS_Private *SiS_Pr, unsigned short ModeNo,
 
    i = 0;
 
+       if (SiS_Pr->ChipType == SIS_730)
+               queuedata = &FQBQData730[0];
+       else
+               queuedata = &FQBQData[0];
+
    if(ModeNo > 0x13) {
 
       /* Get VCLK  */
@@ -2445,12 +2450,6 @@ SiS_SetCRT1FIFO_630(struct SiS_Private *SiS_Pr, unsigned short ModeNo,
       /* Get half colordepth */
       colorth = colortharray[(SiS_Pr->SiS_ModeType - ModeEGA)];
 
-      if(SiS_Pr->ChipType == SIS_730) {
-        queuedata = &FQBQData730[0];
-      } else {
-        queuedata = &FQBQData[0];
-      }
-
       do {
         templ = SiS_CalcDelay2(SiS_Pr, queuedata[i]) * VCLK * colorth;