We need to allocate CMSG_SPACE for the `struct cmsghdr', not the
smaller CMSG_LEN. AFAIK this isn't a real world problem since
the Linux kernel doesn't care about the uninitialized space as
long as memory region belongs to the user, but valgrind complains.
---
lib/PublicInbox/Syscall.pm | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/lib/PublicInbox/Syscall.pm b/lib/PublicInbox/Syscall.pm
index b76a9e8a..4cf45d0f 100644
--- a/lib/PublicInbox/Syscall.pm
+++ b/lib/PublicInbox/Syscall.pm
@@ -398,10 +398,13 @@ no warnings 'once';
my ($sock, $fds, undef, $flags) = @_;
my $iov = pack('P'.TMPL_size_t,
$_[2] // NUL, length($_[2] // NUL) || 1);
+ my $fd_space = scalar(@$fds) * SIZEOF_int;
+ my $msg_controllen = CMSG_SPACE($fd_space);
my $cmsghdr = pack(TMPL_size_t . # cmsg_len
'LL' . # cmsg_level, cmsg_type,
- ('i' x scalar(@$fds)),
- CMSG_LEN(scalar(@$fds) * SIZEOF_int), # cmsg_len
+ ('i' x scalar(@$fds)) . # CMSG_DATA
+ '@'.($msg_controllen - 1).'x1', # pad to space, not len
+ CMSG_LEN($fd_space), # cmsg_len
SOL_SOCKET, SCM_RIGHTS, # cmsg_{level,type}
@$fds); # CMSG_DATA
my $mh = pack('PL' . # msg_name, msg_namelen (socklen_t (U32))
@@ -413,7 +416,7 @@ no warnings 'once';
@BYTES_4_hole,
$iov, 1, # msg_iov, msg_iovlen
$cmsghdr, # msg_control
- CMSG_SPACE(scalar(@$fds) * SIZEOF_int), # msg_controllen
+ $msg_controllen,
0); # msg_flags
my $sent;
my $try = 0;
