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SubjectRe: [PATCH -next] audit: use struct_size() helper in kmalloc()
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在 2021/12/15 2:10, Gustavo A. R. Silva 写道:
> 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@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
thanks, I missed these two places, I will add them in the v2 patch.
>>> @@ -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
>>>
>>>
>>>
>>>
> .

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