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SubjectRe: net: socket: NULL ptr deref in sendmsg
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On Sa, 2014-07-26 at 19:48 +0400, Andrey Ryabinin wrote:
> 2014-07-26 2:15 GMT+04:00 Hannes Frederic Sowa <hannes@stressinduktion.org>:
> > Otherwise I would just set msg_namelen = 0, too, and just not handle
> > passed in NULL pointers to sockaddrs.
> >
>
> I like that, how about such chage:
>
> diff --git a/net/compat.c b/net/compat.c
> index 9a76eaf..bc8aeef 100644
> --- a/net/compat.c
> +++ b/net/compat.c
> @@ -85,7 +85,7 @@ int verify_compat_iovec(struct msghdr *kern_msg,
> struct iovec *kern_iov,
> {
> int tot_len;
>
> - if (kern_msg->msg_namelen) {
> + if (kern_msg->msg_name && kern_msg->msg_namelen) {
> if (mode == VERIFY_READ) {
> int err = move_addr_to_kernel(kern_msg->msg_name,
> kern_msg->msg_namelen,
> @@ -93,10 +93,11 @@ int verify_compat_iovec(struct msghdr *kern_msg,
> struct iovec *kern_iov,
> if (err < 0)
> return err;
> }
> - if (kern_msg->msg_name)
> - kern_msg->msg_name = kern_address;
> - } else
> + kern_msg->msg_name = kern_address;
> + } else {
> kern_msg->msg_name = NULL;
> + kern_msg->msg_namelen = 0;
> + }
>
> tot_len = iov_from_user_compat_to_kern(kern_iov,
> (struct compat_iovec __user
> *)kern_msg->msg_iov,
> diff --git a/net/core/iovec.c b/net/core/iovec.c
> index 827dd6b..e1ec45a 100644
> --- a/net/core/iovec.c
> +++ b/net/core/iovec.c
> @@ -39,7 +39,7 @@ int verify_iovec(struct msghdr *m, struct iovec
> *iov, struct sockaddr_storage *a
> {
> int size, ct, err;
>
> - if (m->msg_namelen) {
> + if (m->msg_name && m->msg_namelen) {
> if (mode == VERIFY_READ) {
> void __user *namep;
> namep = (void __user __force *) m->msg_name;
> @@ -48,10 +48,10 @@ int verify_iovec(struct msghdr *m, struct iovec
> *iov, struct sockaddr_storage *a
> if (err < 0)
> return err;
> }
> - if (m->msg_name)
> - m->msg_name = address;
> + m->msg_name = address;
> } else {
> m->msg_name = NULL;
> + m->msg_namelen = 0;
> }
>
> size = m->msg_iovlen * sizeof(struct iovec);
>
>

LGTM! Can you send a patch?

Thanks,
Hannes




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