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authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-07 13:56:01 -0500
committerMasahiro Yamada <masahiroy@kernel.org>2020-05-26 00:03:16 +0900
commit859c81750130844590a83eff847c6c55e2340ab1 (patch)
tree659355f4f132172c4052fdd2a9f0c705e696d903 /scripts/mod
parent5967577231f9b19acd5a59485e9075964065bbe3 (diff)
modpost,fixdep: 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: Masahiro Yamada <masahiroy@kernel.org>
Diffstat (limited to 'scripts/mod')
-rw-r--r--scripts/mod/modpost.c2
-rw-r--r--scripts/mod/modpost.h2
2 files changed, 2 insertions, 2 deletions
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 5c3c50c5ec52..4d4b979d76be 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -166,7 +166,7 @@ struct symbol {
* (only for external modules) **/
unsigned int is_static:1; /* 1 if symbol is not global */
enum export export; /* Type of export */
- char name[0];
+ char name[];
};
static struct symbol *symbolhash[SYMBOL_HASH_SIZE];
diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index 60dca9b7106b..39f6c29fb568 100644
--- a/scripts/mod/modpost.h
+++ b/scripts/mod/modpost.h
@@ -111,7 +111,7 @@ buf_write(struct buffer *buf, const char *s, int len);
struct namespace_list {
struct namespace_list *next;
- char namespace[0];
+ char namespace[];
};
struct module {