Commit 2422fb52 authored Aug 05, 2020 by Tom Rix Committed by Greg Kroah-Hartman Oct 29, 2020

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: 544393fe ("[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>

parent 32bc70b7

drivers/video/fbdev/sis/init.c

+5 −6

Original line number	Diff line number	Diff line
		@@ -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;