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| author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-07 13:59:07 -0500 |
|---|---|---|
| committer | Johannes Berg <johannes.berg@intel.com> | 2020-05-27 10:02:04 +0200 |
| commit | 3c23215ba8c70c0e9b16beffb7f700a401391e38 (patch) | |
| tree | 3b611a50cec3611a4d5b92af114dabbb8fe39d81 /include/net/mac80211.h | |
| parent | 396fba0a59f3c94d6fd6443fbeabd8bd9e3956eb (diff) | |
| download | linux-3c23215ba8c70c0e9b16beffb7f700a401391e38.tar.bz2 | |
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 'include/net/mac80211.h')
| -rw-r--r-- | include/net/mac80211.h | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/include/net/mac80211.h b/include/net/mac80211.h index 0d48e679efb0..7cb712427df1 100644 --- a/include/net/mac80211.h +++ b/include/net/mac80211.h @@ -230,7 +230,7 @@ struct ieee80211_chanctx_conf { bool radar_enabled; - u8 drv_priv[0] __aligned(sizeof(void *)); + u8 drv_priv[] __aligned(sizeof(void *)); }; /** @@ -1670,7 +1670,7 @@ struct ieee80211_vif { bool txqs_stopped[IEEE80211_NUM_ACS]; /* must be last */ - u8 drv_priv[0] __aligned(sizeof(void *)); + u8 drv_priv[] __aligned(sizeof(void *)); }; static inline bool ieee80211_vif_is_mesh(struct ieee80211_vif *vif) @@ -1798,7 +1798,7 @@ struct ieee80211_key_conf { s8 keyidx; u16 flags; u8 keylen; - u8 key[0]; + u8 key[]; }; #define IEEE80211_MAX_PN_LEN 16 @@ -2053,7 +2053,7 @@ struct ieee80211_sta { struct ieee80211_txq *txq[IEEE80211_NUM_TIDS + 1]; /* must be last */ - u8 drv_priv[0] __aligned(sizeof(void *)); + u8 drv_priv[] __aligned(sizeof(void *)); }; /** @@ -2099,7 +2099,7 @@ struct ieee80211_txq { u8 ac; /* must be last */ - u8 drv_priv[0] __aligned(sizeof(void *)); + u8 drv_priv[] __aligned(sizeof(void *)); }; /** |