• Mateusz Jurczyk's avatar
    netfilter: nfnetlink: Improve input length sanitization in nfnetlink_rcv · f55ce7b0
    Mateusz Jurczyk authored
    Verify that the length of the socket buffer is sufficient to cover the
    nlmsghdr structure before accessing the nlh->nlmsg_len field for further
    input sanitization. If the client only supplies 1-3 bytes of data in
    sk_buff, then nlh->nlmsg_len remains partially uninitialized and
    contains leftover memory from the corresponding kernel allocation.
    Operating on such data may result in indeterminate evaluation of the
    nlmsg_len < NLMSG_HDRLEN expression.
    
    The bug was discovered by a runtime instrumentation designed to detect
    use of uninitialized memory in the kernel. The patch prevents this and
    other similar tools (e.g. KMSAN) from flagging this behavior in the future.
    Signed-off-by: default avatarMateusz Jurczyk <mjurczyk@google.com>
    Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
    f55ce7b0
nfnetlink.c 14.3 KB