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| author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-07 13:53:18 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-05-13 13:59:13 +0200 |
| commit | 84c1e51d7df85332705ffebc40ef135205492036 (patch) | |
| tree | f46ff0b0db248f95b67ee1f9e9b77645851b2d90 /drivers/greybus | |
| parent | dd92b0133a78457e909da1d5916a05c342a897d6 (diff) | |
| download | linux-84c1e51d7df85332705ffebc40ef135205492036.tar.gz linux-84c1e51d7df85332705ffebc40ef135205492036.tar.bz2 linux-84c1e51d7df85332705ffebc40ef135205492036.zip | |
greybus: Replace zero-length array with flexible-array
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]
sizeof(flexible-array-member) triggers a warning because flexible array
members have incomplete type[1]. There are some instances of code in
which the sizeof operator is being incorrectly/erroneously applied to
zero-length arrays and the result is zero. Such instances may be hiding
some bugs. So, this work (flexible-array member conversions) will also
help to get completely rid of those sorts of issues.
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 <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20200507185318.GA14393@embeddedor
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/greybus')
| -rw-r--r-- | drivers/greybus/arpc.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/greybus/arpc.h b/drivers/greybus/arpc.h index c8b83c5cfa79..b9ea81b55b29 100644 --- a/drivers/greybus/arpc.h +++ b/drivers/greybus/arpc.h @@ -21,7 +21,7 @@ struct arpc_request_message { __le16 id; /* RPC unique id */ __le16 size; /* Size in bytes of header + payload */ __u8 type; /* RPC type */ - __u8 data[0]; /* ARPC data */ + __u8 data[]; /* ARPC data */ } __packed; struct arpc_response_message { |