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Subject[PATCH 3.4 175/176] net: compat: Update get_compat_msghdr() to match copy_msghdr_from_user() behaviour
Date
From: Catalin Marinas <catalin.marinas@arm.com>

3.4.107-rc1 review patch. If anyone has any objections, please let me know.

------------------


commit 91edd096e224941131f896b86838b1e59553696a upstream.

Commit db31c55a6fb2 (net: clamp ->msg_namelen instead of returning an
error) introduced the clamping of msg_namelen when the unsigned value
was larger than sizeof(struct sockaddr_storage). This caused a
msg_namelen of -1 to be valid. The native code was subsequently fixed by
commit dbb490b96584 (net: socket: error on a negative msg_namelen).

In addition, the native code sets msg_namelen to 0 when msg_name is
NULL. This was done in commit (6a2a2b3ae075 net:socket: set msg_namelen
to 0 if msg_name is passed as NULL in msghdr struct from userland) and
subsequently updated by 08adb7dabd48 (fold verify_iovec() into
copy_msghdr_from_user()).

This patch brings the get_compat_msghdr() in line with
copy_msghdr_from_user().

Fixes: db31c55a6fb2 (net: clamp ->msg_namelen instead of returning an error)
Cc: David S. Miller <davem@davemloft.net>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[lizf: Backported to 3.4: s/uaddr/tmp1/]
Signed-off-by: Zefan Li <lizefan@huawei.com>
---
net/compat.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/net/compat.c b/net/compat.c
index 2c774d8..5b17509 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -71,6 +71,13 @@ int get_compat_msghdr(struct msghdr *kmsg, struct compat_msghdr __user *umsg)
__get_user(kmsg->msg_controllen, &umsg->msg_controllen) ||
__get_user(kmsg->msg_flags, &umsg->msg_flags))
return -EFAULT;
+
+ if (!tmp1)
+ kmsg->msg_namelen = 0;
+
+ if (kmsg->msg_namelen < 0)
+ return -EINVAL;
+
if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
kmsg->msg_namelen = sizeof(struct sockaddr_storage);
kmsg->msg_name = compat_ptr(tmp1);
--
1.9.1


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