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ALSA: usb-midi: 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
inadvertenly introduced[3] to the codebase from now on.

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 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20200211194224.GA9383@embeddedor
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Gustavo A. R. Silva 2020-02-11 13:42:24 -06:00 committed by Takashi Iwai
parent 9478bd43a2
commit 6c8019d08e
1 changed files with 1 additions and 1 deletions
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2
sound/usb/midi.c
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@ -91,7 +91,7 @@ struct usb_ms_endpoint_descriptor {
__u8 bDescriptorType;
__u8 bDescriptorSubtype;
__u8 bNumEmbMIDIJack;
__u8 baAssocJackID[0];
__u8 baAssocJackID[];
} __attribute__ ((packed));
struct snd_usb_midi_in_endpoint;