From: "Gustavo A. R. Silva" gustavo@embeddedor.com
mainline inclusion from mainline-5.7-rc1 commit c5d6cf903fe8704b65321b2e0c30afebf239247c category: bugfix bugzilla: NA CVE: NA
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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 gustavo@embeddedor.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Yonglong Liu liuyonglong@huawei.com Reviewed-by: li yongxin liyongxin1@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- drivers/net/ethernet/hisilicon/hns/hns_dsaf_ppe.h | 2 +- drivers/net/ethernet/hisilicon/hns/hns_dsaf_rcb.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/hisilicon/hns/hns_dsaf_ppe.h b/drivers/net/ethernet/hisilicon/hns/hns_dsaf_ppe.h index 2721f1f1ab42b..0f0e16f9afc0d 100644 --- a/drivers/net/ethernet/hisilicon/hns/hns_dsaf_ppe.h +++ b/drivers/net/ethernet/hisilicon/hns/hns_dsaf_ppe.h @@ -92,7 +92,7 @@ struct ppe_common_cb { u8 comm_index; /*ppe_common index*/
u32 ppe_num; - struct hns_ppe_cb ppe_cb[0]; + struct hns_ppe_cb ppe_cb[];
};
diff --git a/drivers/net/ethernet/hisilicon/hns/hns_dsaf_rcb.h b/drivers/net/ethernet/hisilicon/hns/hns_dsaf_rcb.h index 3741befb914e5..a9f8059256999 100644 --- a/drivers/net/ethernet/hisilicon/hns/hns_dsaf_rcb.h +++ b/drivers/net/ethernet/hisilicon/hns/hns_dsaf_rcb.h @@ -108,7 +108,7 @@ struct rcb_common_cb { u32 ring_num; u32 desc_num; /* desc num per queue*/
- struct ring_pair_cb ring_pair_cb[0]; + struct ring_pair_cb ring_pair_cb[]; };
int hns_rcb_buf_size2type(u32 buf_size);