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| author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-07 18:19:21 +0300 |
|---|---|---|
| committer | Kalle Valo <kvalo@codeaurora.org> | 2020-05-12 10:31:49 +0300 |
| commit | 103dc3dab295159cb2c5374a0dc499cd3962d49f (patch) | |
| tree | 3508e1c7af12bcbd38845d3b50c7040749220921 /drivers/net/wireless/ath/carl9170 | |
| parent | 4d0f3604c4d181b98104024c837f0e81912f55ef (diff) | |
| download | linux-103dc3dab295159cb2c5374a0dc499cd3962d49f.tar.xz | |
carl9170: 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>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200507151921.GA5083@embeddedor
Diffstat (limited to 'drivers/net/wireless/ath/carl9170')
| -rw-r--r-- | drivers/net/wireless/ath/carl9170/fwcmd.h | 2 | ||||
| -rw-r--r-- | drivers/net/wireless/ath/carl9170/hw.h | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/drivers/net/wireless/ath/carl9170/fwcmd.h b/drivers/net/wireless/ath/carl9170/fwcmd.h index ea1d80f9a50e..56999a3b9d3b 100644 --- a/drivers/net/wireless/ath/carl9170/fwcmd.h +++ b/drivers/net/wireless/ath/carl9170/fwcmd.h @@ -127,7 +127,7 @@ struct carl9170_write_reg { struct carl9170_write_reg_byte { __le32 addr; __le32 count; - u8 val[0]; + u8 val[]; } __packed; #define CARL9170FW_PHY_HT_ENABLE 0x4 diff --git a/drivers/net/wireless/ath/carl9170/hw.h b/drivers/net/wireless/ath/carl9170/hw.h index 08e0ae9c5836..555ad4975970 100644 --- a/drivers/net/wireless/ath/carl9170/hw.h +++ b/drivers/net/wireless/ath/carl9170/hw.h @@ -851,7 +851,7 @@ struct ar9170_stream { __le16 length; __le16 tag; - u8 payload[0]; + u8 payload[]; } __packed __aligned(4); #define AR9170_STREAM_LEN 4 |