From e8dc73c9f9ea554b36093dea23e4ca3b586105d7 Mon Sep 17 00:00:00 2001 From: Gustavo A. R. Silva Date: Wed, 26 Feb 2020 15:26:12 -0600 Subject: xen: 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 Link: https://lore.kernel.org/r/20200226212612.GA4663@embeddedor Reviewed-by: Juergen Gross Signed-off-by: Boris Ostrovsky --- drivers/xen/xen-pciback/pciback.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/xen') diff --git a/drivers/xen/xen-pciback/pciback.h b/drivers/xen/xen-pciback/pciback.h index ce1077e32466..7c95516a860f 100644 --- a/drivers/xen/xen-pciback/pciback.h +++ b/drivers/xen/xen-pciback/pciback.h @@ -52,7 +52,7 @@ struct xen_pcibk_dev_data { unsigned int ack_intr:1; /* .. and ACK-ing */ unsigned long handled; unsigned int irq; /* Saved in case device transitions to MSI/MSI-X */ - char irq_name[0]; /* xen-pcibk[000:04:00.0] */ + char irq_name[]; /* xen-pcibk[000:04:00.0] */ }; /* Used by XenBus and xen_pcibk_ops.c */ -- cgit v1.2.3