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R. Silva" To: Qiang Zhao , Li Yang Subject: [PATCH] soc: fsl: qe: Replace one-element array and use struct_size() helper Message-ID: <20200518221904.GA22274@embeddedor> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kees Cook , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, "Gustavo A. R. Silva" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" The current codebase makes use of one-element arrays in the following form: struct something { int length; u8 data[1]; }; struct something *instance; instance = kmalloc(sizeof(*instance) + size, GFP_KERNEL); instance->length = size; memcpy(instance->data, source, size); but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. So, replace the one-element array with a flexible-array member. Also, make use of the new struct_size() helper to properly calculate the size of struct qe_firmware. This issue was found with the help of Coccinelle and, audited and fixed _manually_. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva --- drivers/soc/fsl/qe/qe.c | 4 ++-- include/soc/fsl/qe/qe.h | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/soc/fsl/qe/qe.c b/drivers/soc/fsl/qe/qe.c index 447146861c2c1..2df20d6f85fa4 100644 --- a/drivers/soc/fsl/qe/qe.c +++ b/drivers/soc/fsl/qe/qe.c @@ -448,7 +448,7 @@ int qe_upload_firmware(const struct qe_firmware *firmware) unsigned int i; unsigned int j; u32 crc; - size_t calc_size = sizeof(struct qe_firmware); + size_t calc_size; size_t length; const struct qe_header *hdr; @@ -480,7 +480,7 @@ int qe_upload_firmware(const struct qe_firmware *firmware) } /* Validate the length and check if there's a CRC */ - calc_size += (firmware->count - 1) * sizeof(struct qe_microcode); + calc_size = struct_size(firmware, microcode, firmware->count); for (i = 0; i < firmware->count; i++) /* diff --git a/include/soc/fsl/qe/qe.h b/include/soc/fsl/qe/qe.h index e282ac01ec081..3feddfec9f87d 100644 --- a/include/soc/fsl/qe/qe.h +++ b/include/soc/fsl/qe/qe.h @@ -307,7 +307,7 @@ struct qe_firmware { u8 revision; /* The microcode version revision */ u8 padding; /* Reserved, for alignment */ u8 reserved[4]; /* Reserved, for future expansion */ - } __attribute__ ((packed)) microcode[1]; + } __packed microcode[]; /* All microcode binaries should be located here */ /* CRC32 should be located here, after the microcode binaries */ } __attribute__ ((packed)); -- 2.26.2