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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-04-06 20:11:55 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-04-07 10:43:44 -0700
commit7ff87182d156e90b59455aac8503da512a1c5dba (patch)
tree475fa3d42741c223bd4188856dbcda9144148095
parentfba4168edecdd2781bcd83cb131977ec1157f87c (diff)
gcov: gcc_3_4: 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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Oberparleiter <oberpar@linux.ibm.com> Link: http://lkml.kernel.org/r/20200302224501.GA14175@embeddedor Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--kernel/gcov/gcc_3_4.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/gcov/gcc_3_4.c b/kernel/gcov/gcc_3_4.c
index 801ee4b0b969..acb83558e5df 100644
--- a/kernel/gcov/gcc_3_4.c
+++ b/kernel/gcov/gcc_3_4.c
@@ -38,7 +38,7 @@ static struct gcov_info *gcov_info_head;
struct gcov_fn_info {
unsigned int ident;
unsigned int checksum;
- unsigned int n_ctrs[0];
+ unsigned int n_ctrs[];
};
/**
@@ -78,7 +78,7 @@ struct gcov_info {
unsigned int n_functions;
const struct gcov_fn_info *functions;
unsigned int ctr_mask;
- struct gcov_ctr_info counts[0];
+ struct gcov_ctr_info counts[];
};
/**
@@ -352,7 +352,7 @@ struct gcov_iterator {
unsigned int count;
int num_types;
- struct type_info type_info[0];
+ struct type_info type_info[];
};
static struct gcov_fn_info *get_func(struct gcov_iterator *iter)