From 5febf6d6ae4d488a5dc388c46d96c17f9556238f Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Mon, 24 Feb 2020 10:14:06 -0600 Subject: scsi: 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") Link: https://lore.kernel.org/r/20200224161406.GA21454@embeddedor Reviewed-by: Lee Duncan Reviewed-by: Satish Kharat Signed-off-by: Gustavo A. R. Silva Signed-off-by: Martin K. Petersen --- include/scsi/iscsi_if.h | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'include/scsi/iscsi_if.h') diff --git a/include/scsi/iscsi_if.h b/include/scsi/iscsi_if.h index 92b11c7e0b4f..b0e240b10bf9 100644 --- a/include/scsi/iscsi_if.h +++ b/include/scsi/iscsi_if.h @@ -311,7 +311,7 @@ enum iscsi_param_type { struct iscsi_param_info { uint32_t len; /* Actual length of the param value */ uint16_t param; /* iscsi param */ - uint8_t value[0]; /* length sized value follows */ + uint8_t value[]; /* length sized value follows */ } __packed; struct iscsi_iface_param_info { @@ -320,7 +320,7 @@ struct iscsi_iface_param_info { uint16_t param; /* iscsi param value */ uint8_t iface_type; /* IPv4 or IPv6 */ uint8_t param_type; /* iscsi_param_type */ - uint8_t value[0]; /* length sized value follows */ + uint8_t value[]; /* length sized value follows */ } __packed; /* @@ -697,7 +697,7 @@ enum iscsi_flashnode_param { struct iscsi_flashnode_param_info { uint32_t len; /* Actual length of the param */ uint16_t param; /* iscsi param value */ - uint8_t value[0]; /* length sized value follows */ + uint8_t value[]; /* length sized value follows */ } __packed; enum iscsi_discovery_parent_type { @@ -815,7 +815,7 @@ struct iscsi_stats { * up to ISCSI_STATS_CUSTOM_MAX */ uint32_t custom_length; - struct iscsi_stats_custom custom[0] + struct iscsi_stats_custom custom[] __attribute__ ((aligned (sizeof(uint64_t)))); }; @@ -946,7 +946,7 @@ struct iscsi_offload_host_stats { * up to ISCSI_HOST_STATS_CUSTOM_MAX */ uint32_t custom_length; - struct iscsi_host_stats_custom custom[0] + struct iscsi_host_stats_custom custom[] __aligned(sizeof(uint64_t)); }; -- cgit v1.2.3