Commit bd018a6a authored by Tetsuo Handa's avatar Tetsuo Handa Committed by Greg Kroah-Hartman

video: fbdev: fix OOB read in vga_8planes_imageblit()

syzbot is reporting OOB read at vga_8planes_imageblit() [1], for
"cdat[y] >> 4" can become a negative value due to "const char *cdat".

[1] https://syzkaller.appspot.com/bug?id=0d7a0da1557dcd1989e00cb3692b26d4173b4132Reported-by: default avatarsyzbot <syzbot+69fbd3e01470f169c8c4@syzkaller.appspotmail.com>
Signed-off-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/90b55ec3-d5b0-3307-9f7c-7ff5c5fd6ad3@i-love.sakura.ne.jpSigned-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 42f07816
......@@ -1121,7 +1121,7 @@ static void vga_8planes_imageblit(struct fb_info *info, const struct fb_image *i
char oldop = setop(0);
char oldsr = setsr(0);
char oldmask = selectmask();
const char *cdat = image->data;
const unsigned char *cdat = image->data;
u32 dx = image->dx;
char __iomem *where;
int y;
......
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