Anant Thazhemadam wrote on Mon, Oct 12, 2020: > In p9_fd_create_unix, checking is performed to see if the addr (passed > as an argument) is NULL or not. > However, no check is performed to see if addr is a valid address, i.e., > it doesn't entirely consist of only 0's. > The initialization of sun_server.sun_path to be equal to this faulty > addr value leads to an uninitialized variable, as detected by KMSAN. > Checking for this (faulty addr) and returning a negative error number > appropriately, resolves this issue.
I'm not sure I agree a fully zeroed address is faulty but I agree we can probably refuse it given userspace can't pass useful abstract addresses here. Just one nitpick but this is otherwise fine - good catch! > Reported-by: syzbot+75d51fe5bf4ebe988...@syzkaller.appspotmail.com > Tested-by: syzbot+75d51fe5bf4ebe988...@syzkaller.appspotmail.com > Signed-off-by: Anant Thazhemadam <anant.thazhema...@gmail.com> > --- > net/9p/trans_fd.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c > index c0762a302162..8f528e783a6c 100644 > --- a/net/9p/trans_fd.c > +++ b/net/9p/trans_fd.c > @@ -1023,7 +1023,7 @@ p9_fd_create_unix(struct p9_client *client, const char > *addr, char *args) > > csocket = NULL; > > - if (addr == NULL) > + if (!addr || !strlen(addr)) Since we don't care about the actual length here, how about checking for addr[0] directly? That'll spare a strlen() call in the valid case. Well, I guess it doesn't really matter -- I'll queue this up anyway and update if you resend. Thanks, -- Dominique
