| Message ID | 20200211210427.GA28952@embeddedor (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | apparmor: Replace zero-length array with flexible-array member | expand |
Hi all, Friendly ping: Who can take this? Thanks -- Gustavo On 2/11/20 15:04, Gustavo A. R. Silva wrote: > 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 > inadvertenly introduced[3] to the codebase from now on. > > 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> > --- > security/apparmor/apparmorfs.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c > index fefee040bf79..cc81080efb63 100644 > --- a/security/apparmor/apparmorfs.c > +++ b/security/apparmor/apparmorfs.c > @@ -804,7 +804,7 @@ static ssize_t query_label(char *buf, size_t buf_len, > struct multi_transaction { > struct kref count; > ssize_t size; > - char data[0]; > + char data[]; > }; > > #define MULTI_TRANSACTION_LIMIT (PAGE_SIZE - sizeof(struct multi_transaction)) >
diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c index fefee040bf79..cc81080efb63 100644 --- a/security/apparmor/apparmorfs.c +++ b/security/apparmor/apparmorfs.c @@ -804,7 +804,7 @@ static ssize_t query_label(char *buf, size_t buf_len, struct multi_transaction { struct kref count; ssize_t size; - char data[0]; + char data[]; }; #define MULTI_TRANSACTION_LIMIT (PAGE_SIZE - sizeof(struct multi_transaction))
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 inadvertenly introduced[3] to the codebase from now on. 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> --- security/apparmor/apparmorfs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)