From fa226f1d81e2d3798d30eaa14550d7f35c35e6f3 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Fri, 21 Feb 2020 09:06:12 -0600 Subject: s390: 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://lkml.kernel.org/r/20200221150612.GA9717@embeddedor Signed-off-by: Gustavo A. R. Silva Signed-off-by: Vasily Gorbik --- drivers/s390/char/sclp_pci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/s390/char/sclp_pci.c') diff --git a/drivers/s390/char/sclp_pci.c b/drivers/s390/char/sclp_pci.c index 995e9196852e..a3e5a5fb0c1e 100644 --- a/drivers/s390/char/sclp_pci.c +++ b/drivers/s390/char/sclp_pci.c @@ -39,7 +39,7 @@ struct err_notify_evbuf { u8 atype; u32 fh; u32 fid; - u8 data[0]; + u8 data[]; } __packed; struct err_notify_sccb { -- cgit v1.2.3