From: Richard Henderson <richard.henderson@linaro.org>
To: Helge Deller <deller@gmx.de>, qemu-devel@nongnu.org
Cc: Sven Schnelle <svens@stackframe.org>,
Richard Henderson <rth@twiddle.net>
Subject: Re: [PATCH 4/4] hw/display/artist.c: fix out of bounds check
Date: Wed, 29 Jul 2020 10:26:48 -0700 [thread overview]
Message-ID: <767c4e05-6018-7f99-4401-cbc1480c3d28@linaro.org> (raw)
In-Reply-To: <20200727214608.32710-5-deller@gmx.de>
On 7/27/20 2:46 PM, Helge Deller wrote:
> - for (i = 0; i < pix_count; i++) {
> + for (i = 0; i < pix_count && offset + i < buf->size; i++) {
> artist_rop8(s, p + offset + pix_count - 1 - i,
> (data & 1) ? (s->plane_mask >> 24) : 0);
> data >>= 1;
This doesn't look right.
You're writing to "offset + pix_count - 1 - i" and yet you're checking bounds
vs "offset + i".
This could be fixed by computing the complete offset into a local variable and
then have an inner if to avoid the write, as you do for the second loop.
But it would be better to precompute the correct loop bounds.
r~
> @@ -398,7 +390,9 @@ static void vram_bit_write(ARTISTState *s, int posx, int posy, bool incr_x,
> for (i = 3; i >= 0; i--) {
> if (!(s->image_bitmap_op & 0x20000000) ||
> s->vram_bitmask & (1 << (28 + i))) {
> - artist_rop8(s, p + offset + 3 - i, data8[ROP8OFF(i)]);
> + if (offset + 3 - i < buf->size) {
> + artist_rop8(s, p + offset + 3 - i, data8[ROP8OFF(i)]);
> + }
> }
> }
> memory_region_set_dirty(&buf->mr, offset, 3);
> @@ -420,7 +414,7 @@ static void vram_bit_write(ARTISTState *s, int posx, int posy, bool incr_x,
> break;
> }
>
> - for (i = 0; i < pix_count; i++) {
> + for (i = 0; i < pix_count && offset + i < buf->size; i++) {
> mask = 1 << (pix_count - 1 - i);
>
> if (!(s->image_bitmap_op & 0x20000000) ||
next prev parent reply other threads:[~2020-07-29 17:27 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-27 21:46 [PATCH 0/4] Various fixes for hppa architecture Helge Deller
2020-07-27 21:46 ` [PATCH 1/4] hw/hppa: Sync hppa_hardware.h file with SeaBIOS sources Helge Deller
2020-07-29 16:36 ` Richard Henderson
2020-07-29 18:21 ` Philippe Mathieu-Daudé
2020-08-01 13:11 ` Helge Deller
2020-07-27 21:46 ` [PATCH 2/4] seabios-hppa: Update to SeaBIOS hppa version 1 Helge Deller
2020-07-27 21:46 ` [PATCH 3/4] hw/hppa: Implement proper SeaBIOS version check Helge Deller
2020-07-27 21:46 ` [PATCH 4/4] hw/display/artist.c: fix out of bounds check Helge Deller
2020-07-29 17:26 ` Richard Henderson [this message]
2020-08-01 13:10 ` Helge Deller
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