Re: [PATCH -next] audit: use struct_size() helper in kmalloc()
On Tue, Dec 14, 2021 at 11:54:48AM -0600, Gustavo A. R. Silva wrote:
On Tue, Dec 14, 2021 at 07:48:54PM +0800, Xiu Jianfeng wrote:
> Make use of struct_size() helper instead of an open-coded calucation.
>
> Link: https://github.com/KSPP/linux/issues/160
> Signed-off-by: Xiu Jianfeng <xiujianfeng(a)huawei.com>
> ---
> kernel/audit.c | 2 +-
> kernel/audit_tree.c | 2 +-
> kernel/auditfilter.c | 2 +-
> 3 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/audit.c b/kernel/audit.c
> index d4084751cfe6..f33028578c60 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
This could use struct_size(), too:
1461 audit_send_reply(skb, seq, AUDIT_SIGNAL_INFO, 0, 0,
1462 sig_data, sizeof(*sig_data) + len);
> @@ -1446,7 +1446,7 @@ static int audit_receive_msg(struct
sk_buff *skb, struct nlmsghdr *nlh)
> if (err)
> return err;
> }
> - sig_data = kmalloc(sizeof(*sig_data) + len, GFP_KERNEL);
> + sig_data = kmalloc(struct_size(sig_data, ctx, len), GFP_KERNEL);
> if (!sig_data) {
> if (audit_sig_sid)
> security_release_secctx(ctx, len);
> diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
> index 72324afcffef..e7315d487163 100644
> --- a/kernel/audit_tree.c
> +++ b/kernel/audit_tree.c
> @@ -94,7 +94,7 @@ static struct audit_tree *alloc_tree(const char *s)
> {
> struct audit_tree *tree;
>
> - tree = kmalloc(sizeof(struct audit_tree) + strlen(s) + 1, GFP_KERNEL);
> + tree = kmalloc(struct_size(tree, pathname, strlen(s) + 1), GFP_KERNEL);
> if (tree) {
> refcount_set(&tree->count, 1);
> tree->goner = 0;
> diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
> index 4173e771650c..19352820b274 100644
> --- a/kernel/auditfilter.c
> +++ b/kernel/auditfilter.c
Also, in this same file the following piece of code could use
struct_size(), too:
1093 skb = audit_make_reply(seq, AUDIT_LIST_RULES, 0, 1,
1094 data,
1095 sizeof(*data) + data->buflen);
Thanks
--
Gustavo
> @@ -637,7 +637,7 @@ static struct audit_rule_data
*audit_krule_to_data(struct audit_krule *krule)
> void *bufp;
> int i;
>
> - data = kmalloc(sizeof(*data) + krule->buflen, GFP_KERNEL);
> + data = kmalloc(struct_size(data, buf, krule->buflen), GFP_KERNEL);
Why don't you also transform the zero-length array in struct
audit_rule_data into a flexible-array member:
508 struct audit_rule_data {
509 __u32 flags; /* AUDIT_PER_{TASK,CALL}, AUDIT_PREPEND */
510 __u32 action; /* AUDIT_NEVER, AUDIT_POSSIBLE, AUDIT_ALWAYS */
511 __u32 field_count;
512 __u32 mask[AUDIT_BITMASK_SIZE]; /* syscall(s) affected */
513 __u32 fields[AUDIT_MAX_FIELDS];
514 __u32 values[AUDIT_MAX_FIELDS];
515 __u32 fieldflags[AUDIT_MAX_FIELDS];
516 __u32 buflen; /* total length of string fields */
517 char buf[0]; /* string fields buffer */
518 };
Thanks
--
Gustavo
> if (unlikely(!data))
> return NULL;
> memset(data, 0, sizeof(*data));
> --
> 2.17.1
>
>
>
>