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    Subject[PATCH 5.9 240/757] video: fbdev: sis: fix null ptr dereference
    Date
    From: Tom Rix <trix@redhat.com>

    [ 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>
    ---
    drivers/video/fbdev/sis/init.c | 11 +++++------
    1 file changed, 5 insertions(+), 6 deletions(-)

    diff --git a/drivers/video/fbdev/sis/init.c b/drivers/video/fbdev/sis/init.c
    index dfe3eb769638b..fde27feae5d0c 100644
    --- 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;

    --
    2.25.1


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