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af_unix: Use offsetof() instead of sizeof().

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The length of the AF_UNIX socket address contains an offset to the member
sun_path of struct sockaddr_un.

Currently, the preceding member is just sun_family, and its type is
sa_family_t and resolved to short.  Therefore, the offset is represented by
sizeof(short).  However, it is not clear and fragile to changes in struct
sockaddr_storage or sockaddr_un.

This commit makes it clear and robust by rewriting sizeof() with
offsetof().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Kuniyuki Iwashima 2021-11-24 11:14:19 +09:00 committed by Jakub Kicinski
parent 442b03c32c
commit 755662ce78
2 changed files with 14 additions and 8 deletions
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19
net/unix/af_unix.c
View File

@ -231,7 +231,8 @@ static int unix_mkname(struct sockaddr_un *sunaddr, int len, unsigned int *hashp
{
*hashp = 0;
if (len <= sizeof(short) || len > sizeof(*sunaddr))
if (len <= offsetof(struct sockaddr_un, sun_path) ||
len > sizeof(*sunaddr))
return -EINVAL;
if (!sunaddr || sunaddr->sun_family != AF_UNIX)
return -EINVAL;
@ -244,7 +245,8 @@ static int unix_mkname(struct sockaddr_un *sunaddr, int len, unsigned int *hashp
* kernel address buffer.
*/
((char *)sunaddr)[len] = 0;
len = strlen(sunaddr->sun_path)+1+sizeof(short);
len = strlen(sunaddr->sun_path) +
offsetof(struct sockaddr_un, sun_path) + 1;
return len;
}
@ -966,7 +968,8 @@ static int unix_autobind(struct socket *sock)
goto out;
err = -ENOMEM;
addr = kzalloc(sizeof(*addr) + sizeof(short) + 16, GFP_KERNEL);
addr = kzalloc(sizeof(*addr) +
offsetof(struct sockaddr_un, sun_path) + 16, GFP_KERNEL);
if (!addr)
goto out;
@ -974,7 +977,8 @@ static int unix_autobind(struct socket *sock)
refcount_set(&addr->refcnt, 1);
retry:
addr->len = sprintf(addr->name->sun_path+1, "%05x", ordernum) + 1 + sizeof(short);
addr->len = sprintf(addr->name->sun_path + 1, "%05x", ordernum) +
offsetof(struct sockaddr_un, sun_path) + 1;
addr->hash = unix_hash_fold(csum_partial(addr->name, addr->len, 0));
addr->hash ^= sk->sk_type;
@ -1156,7 +1160,7 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
sunaddr->sun_family != AF_UNIX)
return -EINVAL;
if (addr_len == sizeof(short))
if (addr_len == offsetof(struct sockaddr_un, sun_path))
return unix_autobind(sock);
err = unix_mkname(sunaddr, addr_len, &hash);
@ -1600,7 +1604,7 @@ static int unix_getname(struct socket *sock, struct sockaddr *uaddr, int peer)
if (!addr) {
sunaddr->sun_family = AF_UNIX;
sunaddr->sun_path[0] = 0;
err = sizeof(short);
err = offsetof(struct sockaddr_un, sun_path);
} else {
err = addr->len;
memcpy(sunaddr, addr->name, addr->len);
@ -3228,7 +3232,8 @@ static int unix_seq_show(struct seq_file *seq, void *v)
seq_putc(seq, ' ');
i = 0;
len = u->addr->len - sizeof(short);
len = u->addr->len -
offsetof(struct sockaddr_un, sun_path);
if (!UNIX_ABSTRACT(s))
len--;
else {

3
net/unix/diag.c
View File

@ -19,7 +19,8 @@ static int sk_diag_dump_name(struct sock *sk, struct sk_buff *nlskb)
if (!addr)
return 0;
return nla_put(nlskb, UNIX_DIAG_NAME, addr->len - sizeof(short),
return nla_put(nlskb, UNIX_DIAG_NAME,
addr->len - offsetof(struct sockaddr_un, sun_path),
addr->name->sun_path);
}