From: Zhang Shurong <zhang_shurong@xxxxxxxxxxx> commit c2d22806aecb24e2de55c30a06e5d6eb297d161d upstream. There is a potential OOB read at fast_imageblit, for "colortab[(*src >> 4)]" can become a negative value due to "const char *s = image->data, *src". This change makes sure the index for colortab always positive or zero. Similar commit: https://patchwork.kernel.org/patch/11746067 Potential bug report: https://groups.google.com/g/syzkaller-bugs/c/9ubBXKeKXf4/m/k-QXy4UgAAAJ Signed-off-by: Zhang Shurong <zhang_shurong@xxxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Helge Deller <deller@xxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/video/fbdev/core/sysimgblt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/video/fbdev/core/sysimgblt.c +++ b/drivers/video/fbdev/core/sysimgblt.c @@ -189,7 +189,7 @@ static void fast_imageblit(const struct u32 fgx = fgcolor, bgx = bgcolor, bpp = p->var.bits_per_pixel; u32 ppw = 32/bpp, spitch = (image->width + 7)/8; u32 bit_mask, eorx, shift; - const char *s = image->data, *src; + const u8 *s = image->data, *src; u32 *dst; const u32 *tab; size_t tablen;
