From 661ea25e5319d0ceaeba80dbc2e083245d91f57a Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Mon, 18 May 2020 17:19:04 -0500 Subject: [PATCH] soc: fsl: qe: Replace one-element array and use struct_size() helper 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 Reviewed-by: Qiang Zhao Signed-off-by: Li Yang --- 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 4471468..2df20d6 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 e282ac0..3feddfe 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)); -- 2.7.4