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 /net/wireless/core.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 'net/wireless/core.h')
-rw-r--r-- | net/wireless/core.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/wireless/core.h b/net/wireless/core.h index 639d41896573..e0e5b3ee9699 100644 --- a/net/wireless/core.h +++ b/net/wireless/core.h @@ -286,7 +286,7 @@ struct cfg80211_cqm_config { u32 rssi_hyst; s32 last_rssi_event_value; int n_rssi_thresholds; - s32 rssi_thresholds[0]; + s32 rssi_thresholds[]; }; void cfg80211_destroy_ifaces(struct cfg80211_registered_device *rdev); |