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author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-02-12 20:35:23 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-02-12 22:57:36 +0100 |
commit | 2f202d03a5785ffaf894f9503193a3767ff88d88 (patch) | |
tree | 59bbd8a407741dcb2f3ee9b5f5a9f03b35639641 /drivers/tty/n_gsm.c | |
parent | tty/serial: 8250_exar: Replace zero-length array with flexible-array member (diff) | |
download | linux-2f202d03a5785ffaf894f9503193a3767ff88d88.tar.xz linux-2f202d03a5785ffaf894f9503193a3767ff88d88.zip |
tty: n_gsm: 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
inadvertenly 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>
Link: https://lore.kernel.org/r/20200212193523.GA28826@embeddedor
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/n_gsm.c')
-rw-r--r-- | drivers/tty/n_gsm.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index f1c90fa2978e..5f8c30f0538e 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -97,7 +97,7 @@ struct gsm_msg { u8 ctrl; /* Control byte + flags */ unsigned int len; /* Length of data block (can be zero) */ unsigned char *data; /* Points into buffer but not at the start */ - unsigned char buffer[0]; + unsigned char buffer[]; }; /* |