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[88.21.202.17]) by smtp.gmail.com with ESMTPSA id y185sm13370681wmy.11.2020.05.23.12.15.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 23 May 2020 12:15:21 -0700 (PDT) From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= To: Helge Deller , qemu-devel@nongnu.org, Richard Henderson , Sven Schnelle Subject: [PATCH 1/3] hw/display/artist: Check offset in draw_line to avoid buffer over-run Date: Sat, 23 May 2020 21:15:15 +0200 Message-Id: <20200523191517.23684-2-f4bug@amsat.org> X-Mailer: git-send-email 2.21.3 In-Reply-To: <20200523191517.23684-1-f4bug@amsat.org> References: <20200523191517.23684-1-f4bug@amsat.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2a00:1450:4864:20::441; envelope-from=philippe.mathieu.daude@gmail.com; helo=mail-wr1-x441.google.com X-detected-operating-system: by eggs.gnu.org: No matching host in p0f cache. That's all we know. X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FORGED_FROMDOMAIN=0.001, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.249, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Alexander Bulekov , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Invalid I/O writes can craft an offset out of the vram_buffer range. We avoid: Program terminated with signal SIGSEGV, Segmentation fault. 284 *dst &= ~plane_mask; (gdb) bt #0 0x000055d5dccdc5c0 in artist_rop8 (s=0x55d5defee510, dst=0x7f8e84ed8216 , val=0 '\000') at hw/display/artist.c:284 #1 0x000055d5dccdcf83 in fill_window (s=0x55d5defee510, startx=22, starty=5674, width=65, height=5697) at hw/display/artist.c:551 #2 0x000055d5dccddfb9 in artist_reg_write (opaque=0x55d5defee510, addr=1051140, val=4265537, size=4) at hw/display/artist.c:902 #3 0x000055d5dcb42a7c in memory_region_write_accessor (mr=0x55d5defeea10, addr=1051140, value=0x7ffe57db08c8, size=4, shift=0, mask=4294967295, attrs=...) at memory.c:483 Reported-by: LLVM libFuzzer Signed-off-by: Philippe Mathieu-Daudé --- hw/display/artist.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/hw/display/artist.c b/hw/display/artist.c index 6261bfe65b..3c2550f6db 100644 --- a/hw/display/artist.c +++ b/hw/display/artist.c @@ -557,7 +557,7 @@ static void fill_window(ARTISTState *s, int startx, int starty, static void draw_line(ARTISTState *s, int x1, int y1, int x2, int y2, bool update_start, int skip_pix, int max_pix) { - struct vram_buffer *buf; + struct vram_buffer *buf = &s->vram_buffer[ARTIST_BUFFER_AP]; uint8_t color; int dx, dy, t, e, x, y, incy, diago, horiz; bool c1; @@ -565,6 +565,12 @@ static void draw_line(ARTISTState *s, int x1, int y1, int x2, int y2, trace_artist_draw_line(x1, y1, x2, y2); + if (x1 * y1 >= buf->size || x2 * y2 >= buf->size) { + qemu_log_mask(LOG_GUEST_ERROR, + "draw_line (%d,%d) (%d,%d)\n", x1, y1, x2, y2); + return; + } + if (update_start) { s->vram_start = (x2 << 16) | y2; } @@ -622,7 +628,6 @@ static void draw_line(ARTISTState *s, int x1, int y1, int x2, int y2, x = x1; y = y1; color = artist_get_color(s); - buf = &s->vram_buffer[ARTIST_BUFFER_AP]; do { if (c1) { -- 2.21.3