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[198.0.35.241]) by smtp.gmail.com with ESMTPSA id e14-20020a17090301ce00b001bba373919bsm4082542plh.261.2023.07.28.16.13.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 28 Jul 2023 16:13:06 -0700 (PDT) From: Kees Cook To: Kalle Valo Cc: Kees Cook , Geert Uytterhoeven , linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH] wifi: ray_cs: Replace 1-element array with flexible array Date: Fri, 28 Jul 2023 16:13:02 -0700 Message-Id: <20230728231245.never.309-kees@kernel.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2098; i=keescook@chromium.org; h=from:subject:message-id; bh=D2CtAwl6CXqSqxRaLIFkwjFO+IpDh8k7U4uCnRppIQc=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBkxEt+LTcBY3bSQZBCTXAzRH9AadW88Qvphq0+C YXJpdqK4H2JAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZMRLfgAKCRCJcvTf3G3A JnEYEACV0z75qof/EEz1U0UD95mEszMnH2IuR2rQZ74usHlFt6IzIwRFnZ2cM6UL4WJdNADtOKa 3uhcp9GFb1pJ1QC0ZBpTanzH5aOAUD3Lj/kFBC+sVjJTKwug0ScKCYAdL7wb7mTLePi6FXR68rE RTx7NwZ0yc2pSYva8LAIQrtyKgKXNPPuf+egh0Yv121pj0icfN1lcDMYYBsFwwtz4pymN7aaGzH 5d8JGzbBHfyBRoSdl3FRG9m6c4BrG2IpSZj2i5T4DgHKofDg1K60fyD1h/V8B2Sqhhx05qXpvVN krkuxUvUqLtdfznPDrO4Eq9oUsuTVYTlTxfxibcmrfdwsbTwfioD2yeQjRaLRIzPJwc1IXB4Va9 4jH2wxpEayWDxJH0yunsKc8K6BWflAYl9qNVdse9qcsqk77Ph9d++zPXvbM+45OzuTePPzbLQvo gY3IcAh52lnpuuogdAJPXKo/NVZwN/Au21r1AsRHkTDeqMLWoqK01DY/nVFUTi0QnXTI/R3zRet qed7hsUR9BxF7ToL2Qv/G6pgAaJwEDpM5xGaBaCW/Qch25fj4niq+cr9r881bRP3siG3G74x2GV 9YIkpt/vlqsKvs8NLuaeJmZC0AxntJ9bkwc9dwq1W6Tbh3iD/IWdT8/zv7qs2wcDulW3Ro/Cw1u demr381 Bj7egpAw== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org The trailing array member of struct tx_buf was defined as a 1-element array, but used as a flexible array. This was resulting in build warnings: In function 'fortify_memset_chk', inlined from 'memset_io' at /kisskb/src/arch/mips/include/asm/io.h:486:2, inlined from 'build_auth_frame' at /kisskb/src/drivers/net/wireless/legacy/ray_cs.c:2697:2: /kisskb/src/include/linux/fortify-string.h:493:25: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning] 493 | __write_overflow_field(p_size_field, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Replace it with an actual flexible array. Binary difference comparison shows a single change in output: │ drivers/net/wireless/legacy/ray_cs.c:883 │ lea 0x1c(%rbp),%r13d │ - cmp $0x7c3,%r13d │ + cmp $0x7c4,%r13d This is from: if (len + TX_HEADER_LENGTH > TX_BUF_SIZE) { specifically: #define TX_BUF_SIZE (2048 - sizeof(struct tx_msg)) This appears to have been originally buggy, so the change is correct. Reported-by: Geert Uytterhoeven Closes: https://lore.kernel.org/all/88f83d73-781d-bdc-126-aa629cb368c@linux-m68k.org Cc: Kalle Valo Cc: linux-wireless@vger.kernel.org Signed-off-by: Kees Cook --- drivers/net/wireless/legacy/rayctl.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/wireless/legacy/rayctl.h b/drivers/net/wireless/legacy/rayctl.h index 2b0f332043d7..1f3bde8ac73d 100644 --- a/drivers/net/wireless/legacy/rayctl.h +++ b/drivers/net/wireless/legacy/rayctl.h @@ -577,7 +577,7 @@ struct tx_msg { struct tib_structure tib; struct phy_header phy; struct mac_header mac; - UCHAR var[1]; + UCHAR var[]; }; /****** ECF Receive Control Structure (RCS) Area at Shared RAM offset 0x0800 */