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authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-07 13:39:09 -0500
committerJohannes Berg <johannes.berg@intel.com>2020-05-27 10:02:03 +0200
commit396fba0a59f3c94d6fd6443fbeabd8bd9e3956eb (patch)
tree8c67834035dab2e879e89f27bdc5927af865ef02 /net/wireless/core.h
parentfedd0fe4e89b009f31eb53ec36dbdf1e457616c0 (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.h2
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);