From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: John Johansen <john.johansen@canonical.com>,
James Morris <jmorris@namei.org>,
"Serge E. Hallyn" <serge@hallyn.com>
Cc: linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org,
"Gustavo A. R. Silva" <gustavo@embeddedor.com>
Subject: [PATCH] apparmor: Replace zero-length array with flexible-array member
Date: Tue, 11 Feb 2020 15:04:27 -0600 [thread overview]
Message-ID: <20200211210427.GA28952@embeddedor> (raw)
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))
--
2.25.0
next reply other threads:[~2020-02-11 21:01 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-11 21:04 Gustavo A. R. Silva [this message]
2020-02-27 12:53 ` [PATCH] apparmor: Replace zero-length array with flexible-array member Gustavo A. R. Silva
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