* [PATCH] net/packet: check length in getsockopt() called with PACKET_HDRLEN
@ 2017-04-25 16:51 Alexander Potapenko
2017-04-25 18:06 ` David Miller
0 siblings, 1 reply; 2+ messages in thread
From: Alexander Potapenko @ 2017-04-25 16:51 UTC (permalink / raw)
To: dvyukov, kcc, edumazet, davem, kuznet; +Cc: linux-kernel, netdev
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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] net/packet: check length in getsockopt() called with PACKET_HDRLEN
2017-04-25 16:51 [PATCH] net/packet: check length in getsockopt() called with PACKET_HDRLEN Alexander Potapenko
@ 2017-04-25 18:06 ` David Miller
0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2017-04-25 18:06 UTC (permalink / raw)
To: glider; +Cc: dvyukov, kcc, edumazet, kuznet, linux-kernel, netdev
From: Alexander Potapenko <glider@google.com>
Date: Tue, 25 Apr 2017 18:51:46 +0200
> 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>
Applied, thanks.
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