[NET]: Fix memory leak in sys_{send,recv}msg() w/compat

From: Dave Johnson <djohnson+linux-kernel@sw.starentnetworks.com>

sendmsg()/recvmsg() syscalls from o32/n32 apps to a 64bit kernel will
cause a kernel memory leak if iov_len > UIO_FASTIOV for each syscall!

This is because both sys_sendmsg() and verify_compat_iovec() kmalloc a
new iovec structure.  Only the one from sys_sendmsg() is free'ed.

I wrote a simple test program to confirm this after identifying the
problem:

http://davej.org/programs/testsendmsg.c

Note that the below fix will break solaris_sendmsg()/solaris_recvmsg() as
it also calls verify_compat_iovec() but expects it to malloc internally.

[ I fixed that. -DaveM ]

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Andrew Morton 2005-08-09 15:29:19 -07:00 committed by David S. Miller
parent 3501466941
commit d64d387372
2 changed files with 121 additions and 85 deletions

View file

@ -16,6 +16,7 @@
#include <linux/net.h>
#include <linux/compat.h>
#include <net/compat.h>
#include <net/sock.h>
#include <asm/uaccess.h>
#include <asm/string.h>
@ -297,121 +298,165 @@ asmlinkage int solaris_sendmsg(int fd, struct sol_nmsghdr __user *user_msg, unsi
{
struct socket *sock;
char address[MAX_SOCK_ADDR];
struct iovec iov[UIO_FASTIOV];
struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
unsigned char ctl[sizeof(struct cmsghdr) + 20];
unsigned char *ctl_buf = ctl;
struct msghdr kern_msg;
int err, total_len;
struct msghdr msg_sys;
int err, ctl_len, iov_size, total_len;
if(msghdr_from_user32_to_kern(&kern_msg, user_msg))
return -EFAULT;
if(kern_msg.msg_iovlen > UIO_MAXIOV)
return -EINVAL;
err = verify_compat_iovec(&kern_msg, iov, address, VERIFY_READ);
if (err < 0)
err = -EFAULT;
if (msghdr_from_user32_to_kern(&msg_sys, user_msg))
goto out;
sock = sockfd_lookup(fd, &err);
if (!sock)
goto out;
/* do not move before msg_sys is valid */
err = -EMSGSIZE;
if (msg_sys.msg_iovlen > UIO_MAXIOV)
goto out_put;
/* Check whether to allocate the iovec area*/
err = -ENOMEM;
iov_size = msg_sys.msg_iovlen * sizeof(struct iovec);
if (msg_sys.msg_iovlen > UIO_FASTIOV) {
iov = sock_kmalloc(sock->sk, iov_size, GFP_KERNEL);
if (!iov)
goto out_put;
}
err = verify_compat_iovec(&msg_sys, iov, address, VERIFY_READ);
if (err < 0)
goto out_freeiov;
total_len = err;
if(kern_msg.msg_controllen) {
struct sol_cmsghdr __user *ucmsg = kern_msg.msg_control;
err = -ENOBUFS;
if (msg_sys.msg_controllen > INT_MAX)
goto out_freeiov;
ctl_len = msg_sys.msg_controllen;
if (ctl_len) {
struct sol_cmsghdr __user *ucmsg = msg_sys.msg_control;
unsigned long *kcmsg;
compat_size_t cmlen;
if (kern_msg.msg_controllen <= sizeof(compat_size_t))
return -EINVAL;
err = -EINVAL;
if (ctl_len <= sizeof(compat_size_t))
goto out_freeiov;
if(kern_msg.msg_controllen > sizeof(ctl)) {
if (ctl_len > sizeof(ctl)) {
err = -ENOBUFS;
ctl_buf = kmalloc(kern_msg.msg_controllen, GFP_KERNEL);
if(!ctl_buf)
ctl_buf = kmalloc(ctl_len, GFP_KERNEL);
if (!ctl_buf)
goto out_freeiov;
}
__get_user(cmlen, &ucmsg->cmsg_len);
kcmsg = (unsigned long *) ctl_buf;
*kcmsg++ = (unsigned long)cmlen;
err = -EFAULT;
if(copy_from_user(kcmsg, &ucmsg->cmsg_level,
kern_msg.msg_controllen - sizeof(compat_size_t)))
if (copy_from_user(kcmsg, &ucmsg->cmsg_level,
ctl_len - sizeof(compat_size_t)))
goto out_freectl;
kern_msg.msg_control = ctl_buf;
msg_sys.msg_control = ctl_buf;
}
kern_msg.msg_flags = solaris_to_linux_msgflags(user_flags);
msg_sys.msg_flags = solaris_to_linux_msgflags(user_flags);
lock_kernel();
sock = sockfd_lookup(fd, &err);
if (sock != NULL) {
if (sock->file->f_flags & O_NONBLOCK)
kern_msg.msg_flags |= MSG_DONTWAIT;
err = sock_sendmsg(sock, &kern_msg, total_len);
sockfd_put(sock);
}
unlock_kernel();
if (sock->file->f_flags & O_NONBLOCK)
msg_sys.msg_flags |= MSG_DONTWAIT;
err = sock_sendmsg(sock, &msg_sys, total_len);
out_freectl:
/* N.B. Use kfree here, as kern_msg.msg_controllen might change? */
if(ctl_buf != ctl)
kfree(ctl_buf);
if (ctl_buf != ctl)
sock_kfree_s(sock->sk, ctl_buf, ctl_len);
out_freeiov:
if(kern_msg.msg_iov != iov)
kfree(kern_msg.msg_iov);
out:
if (iov != iovstack)
sock_kfree_s(sock->sk, iov, iov_size);
out_put:
sockfd_put(sock);
out:
return err;
}
asmlinkage int solaris_recvmsg(int fd, struct sol_nmsghdr __user *user_msg, unsigned int user_flags)
{
struct iovec iovstack[UIO_FASTIOV];
struct msghdr kern_msg;
char addr[MAX_SOCK_ADDR];
struct socket *sock;
struct iovec iovstack[UIO_FASTIOV];
struct iovec *iov = iovstack;
struct msghdr msg_sys;
unsigned long cmsg_ptr;
int err, iov_size, total_len, len;
/* kernel mode address */
char addr[MAX_SOCK_ADDR];
/* user mode address pointers */
struct sockaddr __user *uaddr;
int __user *uaddr_len;
unsigned long cmsg_ptr;
int err, total_len, len = 0;
if(msghdr_from_user32_to_kern(&kern_msg, user_msg))
if (msghdr_from_user32_to_kern(&msg_sys, user_msg))
return -EFAULT;
if(kern_msg.msg_iovlen > UIO_MAXIOV)
return -EINVAL;
uaddr = kern_msg.msg_name;
uaddr_len = &user_msg->msg_namelen;
err = verify_compat_iovec(&kern_msg, iov, addr, VERIFY_WRITE);
if (err < 0)
sock = sockfd_lookup(fd, &err);
if (!sock)
goto out;
err = -EMSGSIZE;
if (msg_sys.msg_iovlen > UIO_MAXIOV)
goto out_put;
/* Check whether to allocate the iovec area*/
err = -ENOMEM;
iov_size = msg_sys.msg_iovlen * sizeof(struct iovec);
if (msg_sys.msg_iovlen > UIO_FASTIOV) {
iov = sock_kmalloc(sock->sk, iov_size, GFP_KERNEL);
if (!iov)
goto out_put;
}
/*
* Save the user-mode address (verify_iovec will change the
* kernel msghdr to use the kernel address space)
*/
uaddr = (void __user *) msg_sys.msg_name;
uaddr_len = &user_msg->msg_namelen;
err = verify_compat_iovec(&msg_sys, iov, addr, VERIFY_WRITE);
if (err < 0)
goto out_freeiov;
total_len = err;
cmsg_ptr = (unsigned long) kern_msg.msg_control;
kern_msg.msg_flags = 0;
cmsg_ptr = (unsigned long) msg_sys.msg_control;
msg_sys.msg_flags = MSG_CMSG_COMPAT;
lock_kernel();
sock = sockfd_lookup(fd, &err);
if (sock != NULL) {
if (sock->file->f_flags & O_NONBLOCK)
user_flags |= MSG_DONTWAIT;
err = sock_recvmsg(sock, &kern_msg, total_len, user_flags);
if(err >= 0)
len = err;
sockfd_put(sock);
}
unlock_kernel();
if (sock->file->f_flags & O_NONBLOCK)
user_flags |= MSG_DONTWAIT;
if(uaddr != NULL && err >= 0)
err = move_addr_to_user(addr, kern_msg.msg_namelen, uaddr, uaddr_len);
if(err >= 0) {
err = __put_user(linux_to_solaris_msgflags(kern_msg.msg_flags), &user_msg->msg_flags);
if(!err) {
/* XXX Convert cmsg back into userspace 32-bit format... */
err = __put_user((unsigned long)kern_msg.msg_control - cmsg_ptr,
&user_msg->msg_controllen);
}
}
if(kern_msg.msg_iov != iov)
kfree(kern_msg.msg_iov);
out:
err = sock_recvmsg(sock, &msg_sys, total_len, user_flags);
if(err < 0)
return err;
return len;
goto out_freeiov;
len = err;
if (uaddr != NULL) {
err = move_addr_to_user(addr, msg_sys.msg_namelen, uaddr, uaddr_len);
if (err < 0)
goto out_freeiov;
}
err = __put_user(linux_to_solaris_msgflags(msg_sys.msg_flags), &user_msg->msg_flags);
if (err)
goto out_freeiov;
err = __put_user((unsigned long)msg_sys.msg_control - cmsg_ptr,
&user_msg->msg_controllen);
if (err)
goto out_freeiov;
err = len;
out_freeiov:
if (iov != iovstack)
sock_kfree_s(sock->sk, iov, iov_size);
out_put:
sockfd_put(sock);
out:
return err;
}

View file

@ -91,20 +91,11 @@ int verify_compat_iovec(struct msghdr *kern_msg, struct iovec *kern_iov,
} else
kern_msg->msg_name = NULL;
if(kern_msg->msg_iovlen > UIO_FASTIOV) {
kern_iov = kmalloc(kern_msg->msg_iovlen * sizeof(struct iovec),
GFP_KERNEL);
if(!kern_iov)
return -ENOMEM;
}
tot_len = iov_from_user_compat_to_kern(kern_iov,
(struct compat_iovec __user *)kern_msg->msg_iov,
kern_msg->msg_iovlen);
if(tot_len >= 0)
kern_msg->msg_iov = kern_iov;
else if(kern_msg->msg_iovlen > UIO_FASTIOV)
kfree(kern_iov);
return tot_len;
}