Evgeniy Polyakov wrote: > When application is bound to group N and it is less than 32 > and has first bit set (I tested with 1, 3, 5) and kernel broadcasts > events to group number 1, application will receive messages, even if > 1. it was not subscribed to that group > 2. it was bound to different group > > Attached trivial test module and userspace program. > make > insmod nltest.ko > ./nluser -g5 > > see the dmesg. > Test module sends data to group number 1, but application is bound and > subscribed to group 5, but still receives messages. > > This issue happens due to the following check in do_one_broadcast(): > > if (nlk->pid == p->pid || p->group - 1 >= nlk->ngroups || > !test_bit(p->group - 1, nlk->groups)) > > nlk->groups is set at bind time to the userspace provided bind group. > So in above case it will be 5. > But above test_bit() is supposed to check subscribed groups, which are > set using set_bit(users_group - 1, nlk->groups). > So when kernelspace broadcasts to group 1 above test_bit() returns true > and message is delivered to the wrong socket. > > Attached patch removes nlk->groups[0] assignment at bind time since it > is completely meaningless due to subscription introduction. > nltest.c - simple test module which broadcasts events to group 1. > nluser.c - userspace application which receives data from socket bound > to specified group.
This seems to be a misunderstanding, subscribing to groups using bind() is kept for compatibility and doesn't use group numbers but bitmasks. - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
