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authorDavid S. Miller <davem@davemloft.net>2010-10-28 11:41:55 -0700
committerDavid S. Miller <davem@davemloft.net>2010-10-28 11:47:52 -0700
commit8acfe468b0384e834a303f08ebc4953d72fb690a (patch)
tree7ecee335efdbd283a122bcba1d5d9b533906142a
parent349f6c5c5d827db909a69e5b9e844e8623c8e881 (diff)
downloadlinux-8acfe468b0384e834a303f08ebc4953d72fb690a.tar.gz
net: Limit socket I/O iovec total length to INT_MAX.
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 <davem@davemloft.net>
-rw-r--r--include/linux/socket.h2
-rw-r--r--net/compat.c10
-rw-r--r--net/core/iovec.c20
3 files changed, 16 insertions, 16 deletions
diff --git a/include/linux/socket.h b/include/linux/socket.h
index 5146b50202c..86b652fabf6 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -322,7 +322,7 @@ 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 63d260e8147..3649d589536 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -41,10 +41,12 @@ 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 72aceb1fe4f..c40f27e7d20 100644
--- a/net/core/iovec.c
+++ b/net/core/iovec.c
@@ -35,10 +35,9 @@
* 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) {
@@ -62,14 +61,13 @@ 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;