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| author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-07 22:19:48 +0300 |
|---|---|---|
| committer | Bjorn Andersson <bjorn.andersson@linaro.org> | 2020-05-13 01:00:48 +0300 |
| commit | 4f05fc33bebdc7d69259c412dd21d09751827dbd (patch) | |
| tree | a35f9bc30082c963b1539c1e0795e4182d0df1ca /drivers/rpmsg | |
| parent | 075894d45656fe9aeced4f34ef692b52791d78dc (diff) | |
| download | linux-4f05fc33bebdc7d69259c412dd21d09751827dbd.tar.xz | |
rpmsg: 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/20200507191948.GA16053@embeddedor
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Diffstat (limited to 'drivers/rpmsg')
| -rw-r--r-- | drivers/rpmsg/virtio_rpmsg_bus.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c index 376ebbf880d6..07d4f3374098 100644 --- a/drivers/rpmsg/virtio_rpmsg_bus.c +++ b/drivers/rpmsg/virtio_rpmsg_bus.c @@ -89,7 +89,7 @@ struct rpmsg_hdr { u32 reserved; u16 len; u16 flags; - u8 data[0]; + u8 data[]; } __packed; /** |