From 6bc3f3979edce0b11deb685a4c817abb7d74b227 Mon Sep 17 00:00:00 2001 From: Gustavo A. R. Silva Date: Thu, 20 Feb 2020 07:20:17 -0600 Subject: USB: 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/20200220132017.GA29262@embeddedor Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/ohci.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/usb/host/ohci.h') diff --git a/drivers/usb/host/ohci.h b/drivers/usb/host/ohci.h index b015b00774b2..27c26ca10bfd 100644 --- a/drivers/usb/host/ohci.h +++ b/drivers/usb/host/ohci.h @@ -337,7 +337,7 @@ typedef struct urb_priv { u16 length; // # tds in this request u16 td_cnt; // tds already serviced struct list_head pending; - struct td *td [0]; // all TDs in this request + struct td *td[]; // all TDs in this request } urb_priv_t; @@ -435,7 +435,7 @@ struct ohci_hcd { struct dentry *debug_dir; /* platform-specific data -- must come last */ - unsigned long priv[0] __aligned(sizeof(s64)); + unsigned long priv[] __aligned(sizeof(s64)); }; -- cgit v1.2.3