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Commit 3aa4c49c authored by Tetsuo Handa's avatar Tetsuo Handa Committed by Greg Kroah-Hartman
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video: fbdev: fix OOB read in vga_8planes_imageblit() 

commit bd018a6a75cebb511bb55a0e7690024be975fe93 upstream.

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=0d7a0da1557dcd1989e00cb3692b26d4173b4132



Reported-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.jp


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 9dd48c39

drivers/video/fbdev/vga16fb.c

+1 −1
Original line number Diff line number Diff line
@@ -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;