Hi Handa-san,
On Thu, Nov 17, 2022 at 4:32 PM Tetsuo Handa penguin-kernel@i-love.sakura.ne.jp wrote:
A kernel built with syzbot's config file reported that
scr_memcpyw(q, save, array3_size(logo_lines, new_cols, 2))
causes uninitialized "save" to be copied.
Signed-off-by: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp
Thanks for your patch, which is now commit a6a00d7e8ffd78d1 ("fbcon: Use kzalloc() in fbcon_prepare_logo()") in v6.1-rc7, and which is being backported to stable.
--- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -577,7 +577,7 @@ static void fbcon_prepare_logo(struct vc_data *vc, struct fb_info *info, if (scr_readw(r) != vc->vc_video_erase_char) break; if (r != q && new_rows >= rows + logo_lines) {
save = kmalloc(array3_size(logo_lines, new_cols, 2),
save = kzalloc(array3_size(logo_lines, new_cols, 2), GFP_KERNEL); if (save) { int i = min(cols, new_cols);
The next line is:
scr_memsetw(save, erase, array3_size(logo_lines, new_cols, 2));
So how can this turn out to be uninitialized later below?
scr_memcpyw(q, save, array3_size(logo_lines, new_cols, 2));
What am I missing?
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds