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| author |   Gustavo A. R. Silva <gustavo@embeddedor.com> | 2020-02-27 12:48:08 -0600 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-03-19 07:41:03 +0100 |
| commit | 3c2faf61fb7152dc1526402bf96ff705f15c0b6b (patch) | |
| tree | b9f4ba3f74787b105a5962359badb4768a564cca /drivers/char | |
| parent | nvmem: jz4780-efuse: fix build warnings on ARCH=x86_64 or riscv (diff) | |
| download | wireguard-linux-3c2faf61fb7152dc1526402bf96ff705f15c0b6b.tar.xz wireguard-linux-3c2faf61fb7152dc1526402bf96ff705f15c0b6b.zip | |
char: mspec: 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>
Link: https://lore.kernel.org/r/20200227184808.GA1925@embeddedor
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/char')
| -rw-r--r-- | drivers/char/mspec.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/char/mspec.c b/drivers/char/mspec.c index a9d9f074fbd6..7d583222e8fa 100644 --- a/drivers/char/mspec.c +++ b/drivers/char/mspec.c @@ -75,7 +75,7 @@ struct vma_data { enum mspec_page_type type; /* Type of pages allocated. */ unsigned long vm_start; /* Original (unsplit) base. */ unsigned long vm_end; /* Original (unsplit) end. */ - unsigned long maddr[0]; /* Array of MSPEC addresses. */ + unsigned long maddr[]; /* Array of MSPEC addresses. */ }; /* |