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authorAlexander Potapenko <glider@google.com>2017-04-25 18:51:46 +0200
committerDavid S. Miller <davem@davemloft.net>2017-04-25 14:05:52 -0400
commitfd2c83b35752f0a8236b976978ad4658df14a59f (patch)
treec655f98ff56baaab4571e8eab59ab6d68fca67cd /net/packet
parent8048ced9beb21a52e3305f3332ae82020619f24e (diff)
net/packet: check length in getsockopt() called with PACKET_HDRLEN
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> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/packet')
-rw-r--r--net/packet/af_packet.c2
1 files changed, 2 insertions, 0 deletions
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) {