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| author | Gustavo A. R. Silva <gustavoars@kernel.org> | 2020-05-07 22:23:02 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-05-08 04:49:04 +0300 |
| commit | 60da7d0bc7482a30817c73fdc8152123d19919f8 (patch) | |
| tree | 7072d1e19f93bc4a7c4a6d565b239d8707f203eb /arch | |
| parent | 57829ea46875770c919ae491dcabf4e2aa5cb385 (diff) | |
| download | linux-60da7d0bc7482a30817c73fdc8152123d19919f8.tar.xz | |
sparc64: 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: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/sparc/kernel/cpumap.c | 2 | ||||
| -rw-r--r-- | arch/sparc/kernel/ds.c | 8 |
2 files changed, 5 insertions, 5 deletions
diff --git a/arch/sparc/kernel/cpumap.c b/arch/sparc/kernel/cpumap.c index 1cb62bfeaa1f..f07ea88a83af 100644 --- a/arch/sparc/kernel/cpumap.c +++ b/arch/sparc/kernel/cpumap.c @@ -50,7 +50,7 @@ struct cpuinfo_tree { /* Offsets into nodes[] for each level of the tree */ struct cpuinfo_level level[CPUINFO_LVL_MAX]; - struct cpuinfo_node nodes[0]; + struct cpuinfo_node nodes[]; }; diff --git a/arch/sparc/kernel/ds.c b/arch/sparc/kernel/ds.c index 75232cbd58bf..522e5b51050c 100644 --- a/arch/sparc/kernel/ds.c +++ b/arch/sparc/kernel/ds.c @@ -87,7 +87,7 @@ struct ds_reg_req { __u64 handle; __u16 major; __u16 minor; - char svc_id[0]; + char svc_id[]; }; struct ds_reg_ack { @@ -701,12 +701,12 @@ struct ds_var_hdr { struct ds_var_set_msg { struct ds_var_hdr hdr; - char name_and_value[0]; + char name_and_value[]; }; struct ds_var_delete_msg { struct ds_var_hdr hdr; - char name[0]; + char name[]; }; struct ds_var_resp { @@ -989,7 +989,7 @@ struct ds_queue_entry { struct ds_info *dp; int req_len; int __pad; - u64 req[0]; + u64 req[]; }; static void process_ds_work(void) |