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author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-07 13:56:01 -0500 |
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committer | Masahiro Yamada <masahiroy@kernel.org> | 2020-05-26 00:03:16 +0900 |
commit | 859c81750130844590a83eff847c6c55e2340ab1 (patch) | |
tree | 659355f4f132172c4052fdd2a9f0c705e696d903 /include | |
parent | 5967577231f9b19acd5a59485e9075964065bbe3 (diff) | |
download | linux-stable-859c81750130844590a83eff847c6c55e2340ab1.tar.gz linux-stable-859c81750130844590a83eff847c6c55e2340ab1.tar.bz2 linux-stable-859c81750130844590a83eff847c6c55e2340ab1.zip |
modpost,fixdep: 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>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Diffstat (limited to 'include')
0 files changed, 0 insertions, 0 deletions