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From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>,
	syzbot <syzbot+04168c8063cfdde1db5e@syzkaller.appspotmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Colin King <colin.king@canonical.com>,
	DRI Development <dri-devel@lists.freedesktop.org>,
	Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Masahiro Yamada <masahiroy@kernel.org>,
	syzkaller-bugs@googlegroups.com,
	Randy Dunlap <rdunlap@infradead.org>
Subject: Re: [PATCH] fbmem: don't allow too huge resolutions
Date: Wed, 1 Sep 2021 00:23:58 +0900	[thread overview]
Message-ID: <5c6d2b95-31d7-0d59-5e62-2593d9a0e1fe@i-love.sakura.ne.jp> (raw)
In-Reply-To: <CAMuHMdWX7s63X_zR9329canbQkPGBVxZNG4O+_=jUut60aGR9g@mail.gmail.com>

On 2021/08/31 15:48, Geert Uytterhoeven wrote:
> Furthermore, this restricts the virtual frame buffer size on 64-bit,
> too, while graphics cards can have much more than 4 GiB of RAM.

Excuse me, but do you mean that some hardware allows allocating more than
UINT_MAX bytes of memory for kernel frame buffer drivers?

> IMHO that should be fixed in vga16fb, too.

According to https://elixir.bootlin.com/linux/v5.14/A/ident/fb_check_var , 
there are 89 files. Randomly picking up drivers/video/fbdev/udlfb.c as
an example. dlfb_is_valid_mode() from dlfb_ops_check_var() is doing

  if (mode->xres * mode->yres > dlfb->sku_pixel_limit)
    return 0;
  return 1;

where max dlfb->sku_pixel_limit seems to be 2048 * 1152 but I think we need
same overflow check. I want to avoid patching individual modules if possible.
That depends on whether some hardware needs to allocate more than UINT_MAX
bytes of memory.


  reply	other threads:[~2021-08-31 15:24 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-14  5:16 [syzbot] BUG: unable to handle kernel paging request in vga16fb_fillrect syzbot
2021-07-14  5:16 ` syzbot
2021-08-30  0:24 ` Randy Dunlap
2021-08-30  2:27   ` Tetsuo Handa
2021-08-30  2:31     ` Randy Dunlap
2021-08-30 16:05       ` [PATCH] fbmem: don't allow too huge resolutions Tetsuo Handa
2021-08-31  6:48         ` Geert Uytterhoeven
2021-08-31  6:48           ` Geert Uytterhoeven
2021-08-31 15:23           ` Tetsuo Handa [this message]
2021-08-31 16:20             ` Daniel Vetter
2021-08-31 16:20               ` Daniel Vetter
2021-08-31 17:19             ` Geert Uytterhoeven
2021-08-31 17:19               ` Geert Uytterhoeven
2021-08-31 18:53               ` Daniel Vetter
2021-08-31 18:53                 ` Daniel Vetter
2021-08-31 18:56                 ` Geert Uytterhoeven
2021-08-31 18:56                   ` Geert Uytterhoeven
2021-08-31 19:04                   ` Daniel Vetter
2021-08-31 19:04                     ` Daniel Vetter
2021-09-01  1:14                     ` [PATCH v2] " Tetsuo Handa
2021-09-01  7:12                       ` Geert Uytterhoeven
2021-09-01  7:12                         ` Geert Uytterhoeven
2021-09-08 10:27                       ` [PATCH v2 (repost)] " Tetsuo Handa
2021-09-08 16:52                         ` Daniel Vetter
2021-08-30 12:00     ` [syzbot] BUG: unable to handle kernel paging request in vga16fb_fillrect Geert Uytterhoeven
2021-08-30 12:00       ` Geert Uytterhoeven
2021-08-30 13:00       ` Dan Carpenter
2021-08-30 13:37         ` Tetsuo Handa
2021-08-30 13:47           ` Dan Carpenter
2021-08-30 14:25             ` Tetsuo Handa
2021-08-30 14:29               ` Dan Carpenter
2021-08-30 14:30               ` Geert Uytterhoeven
2021-08-30 14:30                 ` Geert Uytterhoeven
2021-08-30 14:38                 ` Tetsuo Handa
2021-08-30 14:53                   ` Geert Uytterhoeven
2021-08-30 14:53                     ` Geert Uytterhoeven
2021-08-30 15:00                     ` Geert Uytterhoeven
2021-08-30 15:00                       ` Geert Uytterhoeven

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