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[2001:8b0:1d0::2]) by smtp.gmail.com with ESMTPSA id a26-20020a5d457a000000b00316eb7770b8sm3097631wrc.5.2023.08.18.08.11.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 18 Aug 2023 08:11:00 -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 3/3] ui/vnc-enc-tight: Avoid dynamic stack allocation Date: Fri, 18 Aug 2023 16:10:57 +0100 Message-Id: <20230818151057.1541189-4-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::434; envelope-from=peter.maydell@linaro.org; helo=mail-wr1-x434.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 From: Philippe Mathieu-Daudé Use autofree heap allocation instead of variable-length array on the stack. 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: Philippe Mathieu-Daudé [PMM: expanded commit message] Signed-off-by: Peter Maydell Reviewed-by: Francisco Iglesias --- ui/vnc-enc-tight.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/ui/vnc-enc-tight.c b/ui/vnc-enc-tight.c index ee853dcfcb8..41f559eb837 100644 --- a/ui/vnc-enc-tight.c +++ b/ui/vnc-enc-tight.c @@ -1097,13 +1097,13 @@ static int send_palette_rect(VncState *vs, int x, int y, switch (vs->client_pf.bytes_per_pixel) { case 4: { - size_t old_offset, offset; - uint32_t header[palette_size(palette)]; + size_t old_offset, offset, palette_sz = palette_size(palette); + g_autofree uint32_t *header = g_new(uint32_t, palette_sz); struct palette_cb_priv priv = { vs, (uint8_t *)header }; old_offset = vs->output.offset; palette_iter(palette, write_palette, &priv); - vnc_write(vs, header, sizeof(header)); + vnc_write(vs, header, palette_sz * sizeof(uint32_t)); if (vs->tight->pixel24) { tight_pack24(vs, vs->output.buffer + old_offset, colors, &offset); @@ -1115,11 +1115,12 @@ static int send_palette_rect(VncState *vs, int x, int y, } case 2: { - uint16_t header[palette_size(palette)]; + size_t palette_sz = palette_size(palette); + g_autofree uint16_t *header = g_new(uint16_t, palette_sz); struct palette_cb_priv priv = { vs, (uint8_t *)header }; palette_iter(palette, write_palette, &priv); - vnc_write(vs, header, sizeof(header)); + vnc_write(vs, header, palette_sz * sizeof(uint16_t)); tight_encode_indexed_rect16(vs->tight->tight.buffer, w * h, palette); break; }