Skip to content

Commit

Permalink
char: virtio: Replace zero-length array with flexible-array member
Browse files Browse the repository at this point in the history
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 7649773 ("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>
  • Loading branch information
Gustavo A. R. Silva authored and Greg Kroah-Hartman committed Feb 14, 2020
1 parent 239a579 commit 1031eb9
Showing 1 changed file with 1 addition and 1 deletion.
2 changes: 1 addition & 1 deletion drivers/char/virtio_console.c
Original file line number Diff line number Diff line change
Expand Up @@ -112,7 +112,7 @@ struct port_buffer {
unsigned int sgpages;

/* sg is used if spages > 0. sg must be the last in is struct */
struct scatterlist sg[0];
struct scatterlist sg[];
};

/*
Expand Down

0 comments on commit 1031eb9

Please sign in to comment.