USB: Replace zero-length array with flexible-array member (6bc3f397) · Commits · 戴 / test

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 ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by:

Gustavo A. R. Silva <gustavo@embeddedor.com> Link: https://lore.kernel.org/r/20200220132017.GA29262@embeddedor Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/atm/usbatm.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -164,7 +164,7 @@ struct usbatm_data {
		unsigned char cell_buf; / holds partial rx cell */
		unsigned int buf_usage;

		struct urb *urbs[0];
		struct urb *urbs[];
		};

		static inline void to_usbatm_driver_data(struct usb_interface intf)

drivers/usb/dwc2/hcd.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -199,7 +199,7 @@ struct dwc2_hcd_urb {
		u32 flags;
		u16 interval;
		struct dwc2_hcd_pipe_info pipe_info;
		struct dwc2_hcd_iso_packet_desc iso_descs[0];
		struct dwc2_hcd_iso_packet_desc iso_descs[];
		};

		/* Phases for control transfers */

drivers/usb/host/ehci-tegra.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -282,7 +282,7 @@ done:
		struct dma_aligned_buffer {
		void *kmalloc_ptr;
		void *old_xfer_buffer;
		u8 data[0];
		u8 data[];
		};

		static void free_dma_aligned_buffer(struct urb *urb)

drivers/usb/host/ehci.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -255,7 +255,7 @@ struct ehci_hcd { /* one per controller */
		struct list_head tt_list;

		/* platform-specific data -- must come last */
		unsigned long priv[0] __aligned(sizeof(s64));
		unsigned long priv[] __aligned(sizeof(s64));
		};

		/* convert between an HCD pointer and the corresponding EHCI_HCD */
		@@ -460,7 +460,7 @@ struct ehci_iso_sched {
		struct list_head td_list;
		unsigned span;
		unsigned first_packet;
		struct ehci_iso_packet packet[0];
		struct ehci_iso_packet packet[];
		};

		/*

drivers/usb/host/fotg210.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -490,7 +490,7 @@ struct fotg210_iso_packet {
		struct fotg210_iso_sched {
		struct list_head td_list;
		unsigned span;
		struct fotg210_iso_packet packet[0];
		struct fotg210_iso_packet packet[];
		};

		/*

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