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authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-09 00:08:05 +0300
committerBjorn Andersson <bjorn.andersson@linaro.org>2020-05-13 01:16:33 +0300
commitc20977721631602eafb263fd89fbafaa11de1ebe (patch)
treeab85c726f193b7f19c4c87a40c08a94df21a1283
parent91160150aba03d0c173b3f5c859a795cc701bb8d (diff)
downloadlinux-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.c2
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[];
};
/**