From: "Gustavo A. R. Silva" <gustavoars@kernel.org>
To: Qiang Zhao <qiang.zhao@nxp.com>, Li Yang <leoyang.li@nxp.com>
Cc: linuxppc-dev@lists.ozlabs.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
"Gustavo A. R. Silva" <gustavo@embeddedor.com>,
Kees Cook <keescook@chromium.org>
Subject: [PATCH] soc: fsl: qe: Replace one-element array and use struct_size() helper
Date: Mon, 18 May 2020 17:19:04 -0500 [thread overview]
Message-ID: <20200518221904.GA22274@embeddedor> (raw)
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 <gustavoars@kernel.org>
---
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
next reply other threads:[~2020-05-18 22:14 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-18 22:19 Gustavo A. R. Silva [this message]
2020-05-18 22:56 ` [PATCH] soc: fsl: qe: Replace one-element array and use struct_size() helper Kees Cook
2020-05-20 23:52 ` Li Yang
2020-05-21 0:01 ` Gustavo A. R. Silva
2020-05-21 3:24 ` Kees Cook
2020-05-22 21:21 ` Li Yang
2020-05-25 2:47 ` Qiang Zhao
2020-05-26 19:56 ` Li Yang
2020-05-19 3:37 ` Qiang Zhao
2020-05-22 21:23 ` Li Yang
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