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| author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-07 21:59:07 +0300 |
|---|---|---|
| committer | Johannes Berg <johannes.berg@intel.com> | 2020-05-27 11:02:04 +0300 |
| commit | 3c23215ba8c70c0e9b16beffb7f700a401391e38 (patch) | |
| tree | 3b611a50cec3611a4d5b92af114dabbb8fe39d81 /net/mac80211/ieee80211_i.h | |
| parent | 396fba0a59f3c94d6fd6443fbeabd8bd9e3956eb (diff) | |
| download | linux-3c23215ba8c70c0e9b16beffb7f700a401391e38.tar.xz | |
mac80211: 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/20200507185907.GA15102@embeddedor
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Diffstat (limited to 'net/mac80211/ieee80211_i.h')
| -rw-r--r-- | net/mac80211/ieee80211_i.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h index 8cbae66b5cdb..2d1b6cb75497 100644 --- a/net/mac80211/ieee80211_i.h +++ b/net/mac80211/ieee80211_i.h @@ -267,7 +267,7 @@ struct probe_resp { struct rcu_head rcu_head; int len; u16 csa_counter_offsets[IEEE80211_MAX_CSA_COUNTERS_NUM]; - u8 data[0]; + u8 data[]; }; struct ps_data { |