Hello Mikhail, On 11/19/19 6:31 PM, Mikhail Golubev wrote: > The structure 'struct sockaddr_vm' has additional element 'unsigned char > svm_zero[]' since version v3.9-rc1 (include/uapi/linux/vm_sockets.h). > Linux kernel checks that this element is zeroed > (net/vmw_vsock/vsock_addr.c). Reflect this on the vsock man page. > > Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=205583 > Signed-off-by: Mikhail Golubev <Mikhail.Golubev@xxxxxxxxxxxxxxx> > --- > man7/vsock.7 | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/man7/vsock.7 b/man7/vsock.7 > index 23c67548f..145057719 100644 > --- a/man7/vsock.7 > +++ b/man7/vsock.7 > @@ -95,6 +95,7 @@ struct sockaddr_vm { > unsigned short svm_reserved1; > unsigned int svm_port; /* Port # in host byte order */ > unsigned int svm_cid; /* Address in host byte order */ > + unsigned char svm_zero[]; > }; > .EE > .in > @@ -113,6 +114,8 @@ Only a process with the > capability may > .BR bind (2) > to these port numbers. > +.I svm_zero > +is always set to 0. > .PP > There are several special addresses: > .B VMADDR_CID_ANY Thanks for the patch. I applied it, and tweaked the wording also. In addition, I think we must describe the size of the field, since the use of an open-ended array at the end of a struct has a specific (different) meaning in C. So, in the end the change looks as below. Cheers, Michael diff --git a/man7/vsock.7 b/man7/vsock.7 index 23c67548f..1adc3084b 100644 --- a/man7/vsock.7 +++ b/man7/vsock.7 @@ -95,6 +95,11 @@ struct sockaddr_vm { unsigned short svm_reserved1; unsigned int svm_port; /* Port # in host byte order */ unsigned int svm_cid; /* Address in host byte order */ + unsigned char svm_zero[sizeof(struct sockaddr) \- + sizeof(sa_family_t) \- + sizeof(unsigned short) \- + sizeof(unsigned int) \- + sizeof(unsigned int)]; }; .EE .in @@ -113,6 +118,8 @@ Only a process with the capability may .BR bind (2) to these port numbers. +.I svm_zero +must be zero-filled. .PP There are several special addresses: .B VMADDR_CID_ANY -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/
