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 --- include/linux/usb/audio-v2.h | 2 +- include/linux/usb/audio-v3.h | 2 +- include/linux/usb/gadget.h | 2 +- include/linux/usb/hcd.h | 2 +- 4 files changed, 4 insertions(+), 4 deletions(-) (limited to 'include/linux/usb') diff --git a/include/linux/usb/audio-v2.h b/include/linux/usb/audio-v2.h index ba4b3e3327ff..5e31740c7e40 100644 --- a/include/linux/usb/audio-v2.h +++ b/include/linux/usb/audio-v2.h @@ -153,7 +153,7 @@ struct uac2_feature_unit_descriptor { __u8 bSourceID; /* bmaControls is actually u32, * but u8 is needed for the hybrid parser */ - __u8 bmaControls[0]; /* variable length */ + __u8 bmaControls[]; /* variable length */ } __attribute__((packed)); /* 4.9.2 Class-Specific AS Interface Descriptor */ diff --git a/include/linux/usb/audio-v3.h b/include/linux/usb/audio-v3.h index 6b708434b7f9..c69a6f2e6837 100644 --- a/include/linux/usb/audio-v3.h +++ b/include/linux/usb/audio-v3.h @@ -109,7 +109,7 @@ struct uac3_feature_unit_descriptor { __u8 bSourceID; /* bmaControls is actually u32, * but u8 is needed for the hybrid parser */ - __u8 bmaControls[0]; /* variable length */ + __u8 bmaControls[]; /* variable length */ /* wFeatureDescrStr omitted */ } __attribute__((packed)); diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h index 124462d65eac..9411c08a5c7e 100644 --- a/include/linux/usb/gadget.h +++ b/include/linux/usb/gadget.h @@ -767,7 +767,7 @@ struct usb_gadget_strings { struct usb_gadget_string_container { struct list_head list; - u8 *stash[0]; + u8 *stash[]; }; /* put descriptor for string with that id into buf (buflen >= 256) */ diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h index 712b2a603645..e12105ed3834 100644 --- a/include/linux/usb/hcd.h +++ b/include/linux/usb/hcd.h @@ -228,7 +228,7 @@ struct usb_hcd { /* The HC driver's private data is stored at the end of * this structure. */ - unsigned long hcd_priv[0] + unsigned long hcd_priv[] __attribute__ ((aligned(sizeof(s64)))); }; -- cgit v1.2.3-59-g8ed1b