From 02042a4cf472a1362e39da72a1d992d59a58a0ab Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Wed, 12 Feb 2020 18:44:26 -0600 Subject: [PATCH] serial: 8250_pci: 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/20200213004426.GA7886@embeddedor.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_pci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c index 939685fed396..0804469ff052 100644 --- a/drivers/tty/serial/8250/8250_pci.c +++ b/drivers/tty/serial/8250/8250_pci.c @@ -53,7 +53,7 @@ struct serial_private { unsigned int nr; struct pci_serial_quirk *quirk; const struct pciserial_board *board; - int line[0]; + int line[]; }; static const struct pci_device_id pci_use_msi[] = { -- 2.30.2