From: Alexander Potapenko <glider@google.com>
To: dvyukov@google.com, kcc@google.com, edumazet@google.com,
davem@davemloft.net, kuznet@ms2.inr.ac.ru
Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Subject: [PATCH] net/packet: check length in getsockopt() called with PACKET_HDRLEN
Date: Tue, 25 Apr 2017 18:51:46 +0200 [thread overview]
Message-ID: <20170425165146.25075-1-glider@google.com> (raw)
In the case getsockopt() is called with PACKET_HDRLEN and optlen < 4
|val| remains uninitialized and the syscall may behave differently
depending on its value, and even copy garbage to userspace on certain
architectures. To fix this we now return -EINVAL if optlen is too small.
This bug has been detected with KMSAN.
Signed-off-by: Alexander Potapenko <glider@google.com>
---
The previous versions of this patch were called "net/packet: initialize
val in packet_getsockopt()"
v3: - change patch summary, return -EINVAL for optlen < sizeof(int)
v2: - if len < sizeof(int), make it 0
---
net/packet/af_packet.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 8489beff5c25..ea81ccf3c7d6 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -3836,6 +3836,8 @@ static int packet_getsockopt(struct socket *sock, int level, int optname,
case PACKET_HDRLEN:
if (len > sizeof(int))
len = sizeof(int);
+ if (len < sizeof(int))
+ return -EINVAL;
if (copy_from_user(&val, optval, len))
return -EFAULT;
switch (val) {
--
2.13.0.rc0.306.g87b477812d-goog
next reply other threads:[~2017-04-25 16:52 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-25 16:51 Alexander Potapenko [this message]
2017-04-25 18:06 ` [PATCH] net/packet: check length in getsockopt() called with PACKET_HDRLEN David Miller
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