From ee3bc9c2232a5227ed8d5587759bf74a5413d7f9 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Mon, 2 Mar 2020 06:23:05 -0600 Subject: [PATCH] r8152: Replace zero-length array with flexible-array member The current codebase makes use of the zero-length array language extension to the C90 standard, 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. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [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 Signed-off-by: David S. Miller --- drivers/net/usb/r8152.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c index 709578f4d060..b8d2722a1b33 100644 --- a/drivers/net/usb/r8152.c +++ b/drivers/net/usb/r8152.c @@ -891,7 +891,7 @@ struct fw_block { struct fw_header { u8 checksum[32]; char version[RTL_VER_SIZE]; - struct fw_block blocks[0]; + struct fw_block blocks[]; } __packed; /** @@ -930,7 +930,7 @@ struct fw_mac { __le32 reserved; __le16 fw_ver_reg; u8 fw_ver_data; - char info[0]; + char info[]; } __packed; /** @@ -982,7 +982,7 @@ struct fw_phy_nc { __le16 bp_start; __le16 bp_num; __le16 bp[4]; - char info[0]; + char info[]; } __packed; enum rtl_fw_type { -- GitLab