From d9de63daf855ea965bd7e8af55f22c40551835d5 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Thu, 28 Oct 2010 11:41:55 -0700 Subject: [PATCH] net: Limit socket I/O iovec total length to INT_MAX. commit 8acfe468b0384e834a303f08ebc4953d72fb690a upstream. This helps protect us from overflow issues down in the individual protocol sendmsg/recvmsg handlers. Once we hit INT_MAX we truncate out the rest of the iovec by setting the iov_len members to zero. This works because: 1) For SOCK_STREAM and SOCK_SEQPACKET sockets, partial writes are allowed and the application will just continue with another write to send the rest of the data. 2) For datagram oriented sockets, where there must be a one-to-one correspondance between write() calls and packets on the wire, INT_MAX is going to be far larger than the packet size limit the protocol is going to check for and signal with -EMSGSIZE. Based upon a patch by Linus Torvalds. Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- include/linux/socket.h | 2 +- net/compat.c | 10 ++++++---- net/core/iovec.c | 20 +++++++++----------- 3 files changed, 16 insertions(+), 16 deletions(-) diff --git a/include/linux/socket.h b/include/linux/socket.h index b2aada6cf14d..7b3aae2052a6 100644 --- a/include/linux/socket.h +++ b/include/linux/socket.h @@ -313,7 +313,7 @@ extern int csum_partial_copy_fromiovecend(unsigned char *kdata, int offset, unsigned int len, __wsum *csump); -extern long verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr *address, int mode); +extern int verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr *address, int mode); extern int memcpy_toiovec(struct iovec *v, unsigned char *kdata, int len); extern int memcpy_toiovecend(const struct iovec *v, unsigned char *kdata, int offset, int len); diff --git a/net/compat.c b/net/compat.c index a1fb1b079a82..73462196de3a 100644 --- a/net/compat.c +++ b/net/compat.c @@ -40,10 +40,12 @@ static inline int iov_from_user_compat_to_kern(struct iovec *kiov, compat_size_t len; if (get_user(len, &uiov32->iov_len) || - get_user(buf, &uiov32->iov_base)) { - tot_len = -EFAULT; - break; - } + get_user(buf, &uiov32->iov_base)) + return -EFAULT; + + if (len > INT_MAX - tot_len) + len = INT_MAX - tot_len; + tot_len += len; kiov->iov_base = compat_ptr(buf); kiov->iov_len = (__kernel_size_t) len; diff --git a/net/core/iovec.c b/net/core/iovec.c index 8cee101bc4de..f911e665a7db 100644 --- a/net/core/iovec.c +++ b/net/core/iovec.c @@ -36,10 +36,9 @@ * in any case. */ -long verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr *address, int mode) +int verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr *address, int mode) { - int size, ct; - long err; + int size, ct, err; if (m->msg_namelen) { if (mode == VERIFY_READ) { @@ -61,14 +60,13 @@ long verify_iovec(struct msghdr *m, struct iovec *iov, struct sockaddr *address, err = 0; for (ct = 0; ct < m->msg_iovlen; ct++) { - err += iov[ct].iov_len; - /* - * Goal is not to verify user data, but to prevent returning - * negative value, which is interpreted as errno. - * Overflow is still possible, but it is harmless. - */ - if (err < 0) - return -EMSGSIZE; + size_t len = iov[ct].iov_len; + + if (len > INT_MAX - err) { + len = INT_MAX - err; + iov[ct].iov_len = len; + } + err += len; } return err; -- 2.39.5