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| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-02-26 15:20:00 -0600 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-02-27 12:06:20 -0800 |
| commit | da60fbe7ef942d64b4d80e99cc9b0205db5964b9 (patch) | |
| tree | ec1ffd9f3659a9ded8c02d4c3111364d8677b5d2 /drivers/nfc | |
| parent | 6dd7f1a1fe20222d152875935f3ee0a009342ade (diff) | |
| download | lwn-da60fbe7ef942d64b4d80e99cc9b0205db5964b9.tar.gz lwn-da60fbe7ef942d64b4d80e99cc9b0205db5964b9.zip | |
NFC: Replace zero-length array with flexible-array member
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]
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 <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/nfc')
| -rw-r--r-- | drivers/nfc/fdp/fdp.c | 2 | ||||
| -rw-r--r-- | drivers/nfc/st21nfca/dep.c | 4 |
2 files changed, 3 insertions, 3 deletions
diff --git a/drivers/nfc/fdp/fdp.c b/drivers/nfc/fdp/fdp.c index 0cc9ac856fe2..7c0b1e6b80ff 100644 --- a/drivers/nfc/fdp/fdp.c +++ b/drivers/nfc/fdp/fdp.c @@ -76,7 +76,7 @@ static u8 nci_core_get_config_otp_ram_version[5] = { struct nci_core_get_config_rsp { u8 status; u8 count; - u8 data[0]; + u8 data[]; }; static int fdp_nci_create_conn(struct nci_dev *ndev) diff --git a/drivers/nfc/st21nfca/dep.c b/drivers/nfc/st21nfca/dep.c index 60acdfd1cb8c..a1d69f9b2d4a 100644 --- a/drivers/nfc/st21nfca/dep.c +++ b/drivers/nfc/st21nfca/dep.c @@ -66,7 +66,7 @@ struct st21nfca_atr_req { u8 bsi; u8 bri; u8 ppi; - u8 gbi[0]; + u8 gbi[]; } __packed; struct st21nfca_atr_res { @@ -79,7 +79,7 @@ struct st21nfca_atr_res { u8 bri; u8 to; u8 ppi; - u8 gbi[0]; + u8 gbi[]; } __packed; struct st21nfca_psl_req { |