CVE-2017-7645

El servidor NFSv2/NFSv3 en el subsistema nfsd en el Kernel de Linux hasta la versión 4.10.11 permite a atacantes remotos provocar una denegación de servicio (caída de sistema) a través de una respuesta RPC larga, relacionada con net/sunrpc/svc.c, fs/nfsd/nfs3xdr.c y fs/nfsd/nfsxdr.c.

The NFS2/3 RPC client could send long arguments to the NFS server. These encoded arguments are stored in an array of memory pages, and accessed using pointer variables. Arbitrarily long arguments could make these pointers point outside the array and cause an out-of-bounds memory access. A remote user or program could use this flaw to crash the kernel, resulting in denial of service.

An update that solves 7 vulnerabilities and has one errata is now available. This update for the Linux Kernel 4.4.21-69 fixes several issues. The following security bugs were fixed. A bug in inotify code allowed local users to escalate privilege. The NFSv4 server in the Linux kernel did not properly validate the layout type when processing the NFSv4 pNFS GETDEVICEINFO or LAYOUTGET operand in a UDP packet from a remote attacker. This type value is uninitialized upon encountering certain error conditions. This value is used as an array index for dereferencing, which leads to an OOPS and eventually a DoS of knfsd and a soft-lockup of the whole system The NFSv2/NFSv3 server in the nfsd subsystem in the Linux kernel allowed remote attackers to cause a denial of service (system crash) via a long RPC reply, related to net/sunrpc/svc.c, fs/nfsd/nfs3xdr.c, and fs/nfsd/nfsxdr.c. Race condition in drivers/tty/n_hdlc.c in the Linux kernel allowed local users to gain privileges or cause a denial of service by setting the HDLC line discipline. The __ip6_append_data function in net/ipv6/ip6_output.c in the Linux kernel is too late in checking whether an overwrite of an skb data structure may occur, which allowed local users to cause a denial of service via crafted system calls. The tcp_v6_syn_recv_sock function in net/ipv6/tcp_ipv6.c in the Linux kernel mishandled inheritance, which allowed local users to cause a denial of service or possibly have unspecified other impact via crafted system calls, a related issue to CVE-2017-8890. The inet_csk_clone_lock function in net/ipv4/inet_connection_sock.c in the Linux kernel allowed attackers to cause a denial of service or possibly have unspecified other impact by leveraging use of the accept system call.