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| author | Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-02-21 09:06:12 -0600 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2020-02-27 16:02:21 +0100 |
| commit | fa226f1d81e2d3798d30eaa14550d7f35c35e6f3 (patch) | |
| tree | 2063b7d5c04db419fe443d7a2aa39e1cc21cbe4e /drivers/s390/char | |
| parent | d5d006fa0927c34fa083c8d48e33b1c30b29fd1b (diff) | |
| download | lwn-fa226f1d81e2d3798d30eaa14550d7f35c35e6f3.tar.gz lwn-fa226f1d81e2d3798d30eaa14550d7f35c35e6f3.zip | |
s390: 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")
Link: https://lkml.kernel.org/r/20200221150612.GA9717@embeddedor
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'drivers/s390/char')
| -rw-r--r-- | drivers/s390/char/raw3270.h | 2 | ||||
| -rw-r--r-- | drivers/s390/char/sclp_pci.c | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/drivers/s390/char/raw3270.h b/drivers/s390/char/raw3270.h index 3afaa35f7351..08f36e973b43 100644 --- a/drivers/s390/char/raw3270.h +++ b/drivers/s390/char/raw3270.h @@ -211,7 +211,7 @@ struct string struct list_head update; unsigned long size; unsigned long len; - char string[0]; + char string[]; } __attribute__ ((aligned(8))); static inline struct string * diff --git a/drivers/s390/char/sclp_pci.c b/drivers/s390/char/sclp_pci.c index 995e9196852e..a3e5a5fb0c1e 100644 --- a/drivers/s390/char/sclp_pci.c +++ b/drivers/s390/char/sclp_pci.c @@ -39,7 +39,7 @@ struct err_notify_evbuf { u8 atype; u32 fh; u32 fid; - u8 data[0]; + u8 data[]; } __packed; struct err_notify_sccb { |