path: root/net/compat.c
diff options
authorWei Yongjun <yjwei@cn.fujitsu.com>2007-12-20 14:36:44 -0800
committerDavid S. Miller <davem@davemloft.net>2007-12-20 14:36:44 -0800
commit1ac70e7ad24a88710cf9b6d7ababaefa2b575df0 (patch)
tree175202f238aca605bf916f4871bc7ce04eebddc7 /net/compat.c
parentc5c0f33d8e5b1219c86757e6afffd6f96823e521 (diff)
[NET]: Fix function put_cmsg() which may cause usr application memory overflow
When used function put_cmsg() to copy kernel information to user application memory, if the memory length given by user application is not enough, by the bad length calculate of msg.msg_controllen, put_cmsg() function may cause the msg.msg_controllen to be a large value, such as 0xFFFFFFF0, so the following put_cmsg() can also write data to usr application memory even usr has no valid memory to store this. This may cause usr application memory overflow. int put_cmsg(struct msghdr * msg, int level, int type, int len, void *data) { struct cmsghdr __user *cm = (__force struct cmsghdr __user *)msg->msg_control; struct cmsghdr cmhdr; int cmlen = CMSG_LEN(len); ~~~~~~~~~~~~~~~~~~~~~ int err; if (MSG_CMSG_COMPAT & msg->msg_flags) return put_cmsg_compat(msg, level, type, len, data); if (cm==NULL || msg->msg_controllen < sizeof(*cm)) { msg->msg_flags |= MSG_CTRUNC; return 0; /* XXX: return error? check spec. */ } if (msg->msg_controllen < cmlen) { ~~~~~~~~~~~~~~~~~~~~~~~~ msg->msg_flags |= MSG_CTRUNC; cmlen = msg->msg_controllen; } cmhdr.cmsg_level = level; cmhdr.cmsg_type = type; cmhdr.cmsg_len = cmlen; err = -EFAULT; if (copy_to_user(cm, &cmhdr, sizeof cmhdr)) goto out; if (copy_to_user(CMSG_DATA(cm), data, cmlen - sizeof(struct cmsghdr))) goto out; cmlen = CMSG_SPACE(len); ~~~~~~~~~~~~~~~~~~~~~~~~~~~ If MSG_CTRUNC flags is set, msg->msg_controllen is less than CMSG_SPACE(len), "msg->msg_controllen -= cmlen" will cause unsinged int type msg->msg_controllen to be a large value. ~~~~~~~~~~~~~~~~~~~~~~~~~~~ msg->msg_control += cmlen; msg->msg_controllen -= cmlen; ~~~~~~~~~~~~~~~~~~~~~ err = 0; out: return err; } The same promble exists in put_cmsg_compat(). This patch can fix this problem. Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/compat.c')
1 files changed, 2 insertions, 0 deletions
diff --git a/net/compat.c b/net/compat.c
index d74d82155d78..377e560ab5c9 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -254,6 +254,8 @@ int put_cmsg_compat(struct msghdr *kmsg, int level, int type, int len, void *dat
if (copy_to_user(CMSG_COMPAT_DATA(cm), data, cmlen - sizeof(struct compat_cmsghdr)))
return -EFAULT;
cmlen = CMSG_COMPAT_SPACE(len);
+ if (kmsg->msg_controllen < cmlen)
+ cmlen = kmsg->msg_controllen;
kmsg->msg_control += cmlen;
kmsg->msg_controllen -= cmlen;
return 0;

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