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char: virtio: 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/20200211222941.GA7657@embeddedor
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Gustavo A. R. Silva 2020-02-11 16:29:41 -06:00 committed by Greg Kroah-Hartman
parent 239a5791ff
commit 1031eb90c1
1 changed files with 1 additions and 1 deletions
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2
drivers/char/virtio_console.c
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@ -112,7 +112,7 @@ struct port_buffer {
unsigned int sgpages; unsigned int sgpages;
/* sg is used if spages > 0. sg must be the last in is struct */ /* sg is used if spages > 0. sg must be the last in is struct */
struct scatterlist sg[0]; struct scatterlist sg[];
}; };
/* /*