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&gt; >> --- >> 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 >> >> >> >> .