diff options
| author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-07 13:39:09 -0500 |
|---|---|---|
| committer | Johannes Berg <johannes.berg@intel.com> | 2020-05-27 10:02:03 +0200 |
| commit | 396fba0a59f3c94d6fd6443fbeabd8bd9e3956eb (patch) | |
| tree | 8c67834035dab2e879e89f27bdc5927af865ef02 /include/linux/ieee80211.h | |
| parent | fedd0fe4e89b009f31eb53ec36dbdf1e457616c0 (diff) | |
cfg80211: 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/20200507183909.GA12993@embeddedor
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Diffstat (limited to 'include/linux/ieee80211.h')
| -rw-r--r-- | include/linux/ieee80211.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h index 2153d465d752..0320ca4c7d28 100644 --- a/include/linux/ieee80211.h +++ b/include/linux/ieee80211.h @@ -800,7 +800,7 @@ struct ieee80211_msrment_ie { u8 token; u8 mode; u8 type; - u8 request[0]; + u8 request[]; } __packed; /** @@ -1781,7 +1781,7 @@ struct ieee80211_he_operation { __le32 he_oper_params; __le16 he_mcs_nss_set; /* Optional 0,1,3,4,5,7 or 8 bytes: depends on @he_oper_params */ - u8 optional[0]; + u8 optional[]; } __packed; /** @@ -1793,7 +1793,7 @@ struct ieee80211_he_operation { struct ieee80211_he_spr { u8 he_sr_control; /* Optional 0 to 19 bytes: depends on @he_sr_control */ - u8 optional[0]; + u8 optional[]; } __packed; /** |