diff options
| author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-09 00:08:05 +0300 |
|---|---|---|
| committer | Bjorn Andersson <bjorn.andersson@linaro.org> | 2020-05-13 01:16:33 +0300 |
| commit | c20977721631602eafb263fd89fbafaa11de1ebe (patch) | |
| tree | ab85c726f193b7f19c4c87a40c08a94df21a1283 | |
| parent | 91160150aba03d0c173b3f5c859a795cc701bb8d (diff) | |
| download | linux-c20977721631602eafb263fd89fbafaa11de1ebe.tar.xz | |
firmware: qcom_scm-legacy: 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")
Reviewed-by: Jeffrey Hugo <jhugo@codeaurora.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20200508210805.GA24170@embeddedor
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
| -rw-r--r-- | drivers/firmware/qcom_scm-legacy.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/firmware/qcom_scm-legacy.c b/drivers/firmware/qcom_scm-legacy.c index 8532e7c78ef7..eba6b60bfb61 100644 --- a/drivers/firmware/qcom_scm-legacy.c +++ b/drivers/firmware/qcom_scm-legacy.c @@ -56,7 +56,7 @@ struct scm_legacy_command { __le32 buf_offset; __le32 resp_hdr_offset; __le32 id; - __le32 buf[0]; + __le32 buf[]; }; /** |