From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41190) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bLEtY-0006UG-Jb for qemu-devel@nongnu.org; Thu, 07 Jul 2016 15:23:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bLEtS-00047b-Ev for qemu-devel@nongnu.org; Thu, 07 Jul 2016 15:23:31 -0400 Received: from jessie.kos.to ([212.47.231.226]:35736 helo=pilvi.kos.to) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bLEtS-00047J-8O for qemu-devel@nongnu.org; Thu, 07 Jul 2016 15:23:26 -0400 Date: Thu, 7 Jul 2016 22:23:22 +0300 From: Riku Voipio Message-ID: <20160707192322.GB30964@beaming.home> References: <1467902683-12904-1-git-send-email-peter.maydell@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1467902683-12904-1-git-send-email-peter.maydell@linaro.org> Subject: Re: [Qemu-devel] [PATCH] linux-user: Handle short lengths in host_to_target_sockaddr() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Maydell Cc: qemu-devel@nongnu.org, patches@linaro.org On Thu, Jul 07, 2016 at 03:44:43PM +0100, Peter Maydell wrote: > If userspace specifies a short buffer for a target sockaddr, > the kernel will only copy in as much as it has space for > (or none at all if the length is zero) -- see the kernel > move_addr_to_user() function. Mimic this in QEMU's > host_to_target_sockaddr() routine. > > In particular, this fixes a segfault running the LTP > recvfrom01 test, where the guest makes a recvfrom() > call with a bad buffer pointer and other parameters which > cause the kernel to set the addrlen to zero; because we > did not skip the attempt to swap the sa_family field we > segfaulted on the bad address. > Signed-off-by: Peter Maydell All your patches up to this one applied to linux-user, thanks! Riku > --- > linux-user/syscall.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/linux-user/syscall.c b/linux-user/syscall.c > index 165fd06..6e77d34 100644 > --- a/linux-user/syscall.c > +++ b/linux-user/syscall.c > @@ -1374,12 +1374,19 @@ static inline abi_long host_to_target_sockaddr(abi_ulong target_addr, > { > struct target_sockaddr *target_saddr; > > + if (len == 0) { > + return 0; > + } > + > target_saddr = lock_user(VERIFY_WRITE, target_addr, len, 0); > if (!target_saddr) > return -TARGET_EFAULT; > memcpy(target_saddr, addr, len); > - target_saddr->sa_family = tswap16(addr->sa_family); > - if (addr->sa_family == AF_NETLINK) { > + if (len >= offsetof(struct target_sockaddr, sa_family) + > + sizeof(target_saddr->sa_family)) { > + target_saddr->sa_family = tswap16(addr->sa_family); > + } > + if (addr->sa_family == AF_NETLINK && len >= sizeof(struct sockaddr_nl)) { > struct sockaddr_nl *target_nl = (struct sockaddr_nl *)target_saddr; > target_nl->nl_pid = tswap32(target_nl->nl_pid); > target_nl->nl_groups = tswap32(target_nl->nl_groups); > -- > 1.9.1 >