diff options
| author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-07 13:57:49 -0500 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-05-15 11:58:54 +1000 |
| commit | 0f6be41c60699fd8cdfa93e5e85a306cec1ac1d0 (patch) | |
| tree | 381ccfb63b962062be2ec1a71a8becfa36726ba0 /arch/powerpc | |
| parent | 4e0e45b07d790253643ee05300784ab2156e2d5e (diff) | |
powerpc: 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: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200507185749.GA14994@embeddedor
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/platforms/powermac/nvram.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/powerpc/platforms/powermac/nvram.c b/arch/powerpc/platforms/powermac/nvram.c index dc7a5bae8f1c..853ccc4480e2 100644 --- a/arch/powerpc/platforms/powermac/nvram.c +++ b/arch/powerpc/platforms/powermac/nvram.c @@ -55,7 +55,7 @@ struct chrp_header { u8 cksum; u16 len; char name[12]; - u8 data[0]; + u8 data[]; }; struct core99_header { |