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[2001:8b0:1d0::2]) by smtp.gmail.com with ESMTPSA id a26-20020a5d457a000000b00316eb7770b8sm3097631wrc.5.2023.08.18.08.10.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Aug 2023 08:10:59 -0700 (PDT) From: Peter Maydell To: qemu-devel@nongnu.org Cc: Gerd Hoffmann , =?utf-8?q?Marc-Andr=C3=A9_Lureau?= , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= Subject: [PATCH 1/3] ui/spice-display: Avoid dynamic stack allocation Date: Fri, 18 Aug 2023 16:10:55 +0100 Message-Id: <20230818151057.1541189-2-peter.maydell@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230818151057.1541189-1-peter.maydell@linaro.org> References: <20230818151057.1541189-1-peter.maydell@linaro.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2a00:1450:4864:20::335; envelope-from=peter.maydell@linaro.org; helo=mail-wm1-x335.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Use an autofree heap allocation instead of a variable-length array on the stack in qemu_spice_create_update(). The codebase has very few VLAs, and if we can get rid of them all we can make the compiler error on new additions. This is a defensive measure against security bugs where an on-stack dynamic allocation isn't correctly size-checked (e.g. CVE-2021-3527). Signed-off-by: Peter Maydell Reviewed-by: Philippe Mathieu-Daudé --- I was a little unsure about this allocation given that it's in the display_refresh callback, but the code already does a g_malloc() every time it calls qemu_spice_create_one_update() so one more presumably won't hurt. --- ui/spice-display.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/ui/spice-display.c b/ui/spice-display.c index 3f3f8013d86..0e2fbfb17c1 100644 --- a/ui/spice-display.c +++ b/ui/spice-display.c @@ -189,7 +189,7 @@ static void qemu_spice_create_update(SimpleSpiceDisplay *ssd) { static const int blksize = 32; int blocks = DIV_ROUND_UP(surface_width(ssd->ds), blksize); - int dirty_top[blocks]; + g_autofree int *dirty_top = NULL; int y, yoff1, yoff2, x, xoff, blk, bw; int bpp = surface_bytes_per_pixel(ssd->ds); uint8_t *guest, *mirror; @@ -198,6 +198,7 @@ static void qemu_spice_create_update(SimpleSpiceDisplay *ssd) return; }; + dirty_top = g_new(int, blocks); for (blk = 0; blk < blocks; blk++) { dirty_top[blk] = -1; }