On Mon, Apr 27, 2009 at 12:49:07PM -0400, Chuck Lever wrote:
> On Apr 25, 2009, at 6:17 PM, J. Bruce Fields wrote:
>> On Thu, Apr 23, 2009 at 07:31:25PM -0400, Chuck Lever wrote:
>>> The svc_addr_len() helper function returns -EAFNOSUPPORT if it
>>> doesn't
>>> recognize the address family of the passed-in socket address.
>>> However,
>>> the return type of this function is size_t, which means -EAFNOSUPPORT
>>> is turned into a very large positive value in this case.
>>>
>>> The check in svc_udp_recvfrom() to see if the return value is less
>>> than zero therefore won't work at all.
>>>
>>> Additionally, handle_connect_req() passes this value directly to
>>> memset(). This could cause memset() to clobber a large chunk of
>>> memory
>>> if svc_addr_len() has returned an error. Currently the address
>>> family
>>> of these addresses, however, is known to be supported long before
>>> handle_connect_req() is called, so this isn't a real risk.
>>>
>>> Change the error return value of svc_addr_len() to zero, which fits
>>> in
>>> the range of size_t, and is safer to pass to memset() directly.
>>>
>>> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
>>> ---
>>>
>>> include/linux/sunrpc/svc_xprt.h | 5 +++--
>>> net/sunrpc/svcsock.c | 7 ++++---
>>> 2 files changed, 7 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/
>>> svc_xprt.h
>>> index 0d9cb6e..d790c52 100644
>>> --- a/include/linux/sunrpc/svc_xprt.h
>>> +++ b/include/linux/sunrpc/svc_xprt.h
>>> @@ -118,7 +118,7 @@ static inline unsigned short svc_addr_port(const
>>> struct sockaddr *sa)
>>> return 0;
>>> }
>>>
>>> -static inline size_t svc_addr_len(struct sockaddr *sa)
>>> +static inline size_t svc_addr_len(const struct sockaddr *sa)
>>> {
>>> switch (sa->sa_family) {
>>> case AF_INET:
>>> @@ -126,7 +126,8 @@ static inline size_t svc_addr_len(struct
>>> sockaddr *sa)
>>> case AF_INET6:
>>> return sizeof(struct sockaddr_in6);
>>> }
>>> - return -EAFNOSUPPORT;
>>> +
>>
>> May as well stick a WARN() here too if only as a shorthand way of
>> documenting that this isn't meant to happen.
>
> Sounds reasonable, but:
>
> 1. I thought BUG() was the way to document "shouldn't happen," and
That'd be OK too.
>
> 2. What about all the other static inliney places this "shouldn't
> happen" ?
Such as?
--b.
>
> I guess we kind of gave up on BUG'ing in all these places.
>
>> --b.
>>
>>> + return 0;
>>> }
>>>
>>> static inline unsigned short svc_xprt_local_port(const struct
>>> svc_xprt *xprt)
>>> diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
>>> index af31988..8b08328 100644
>>> --- a/net/sunrpc/svcsock.c
>>> +++ b/net/sunrpc/svcsock.c
>>> @@ -426,13 +426,14 @@ static int svc_udp_recvfrom(struct svc_rqst
>>> *rqstp)
>>> long all[SVC_PKTINFO_SPACE / sizeof(long)];
>>> } buffer;
>>> struct cmsghdr *cmh = &buffer.hdr;
>>> - int err, len;
>>> struct msghdr msg = {
>>> .msg_name = svc_addr(rqstp),
>>> .msg_control = cmh,
>>> .msg_controllen = sizeof(buffer),
>>> .msg_flags = MSG_DONTWAIT,
>>> };
>>> + size_t len;
>>> + int err;
>>>
>>> if (test_and_clear_bit(XPT_CHNGBUF, &svsk->sk_xprt.xpt_flags))
>>> /* udp sockets need large rcvbuf as all pending
>>> @@ -464,8 +465,8 @@ static int svc_udp_recvfrom(struct svc_rqst
>>> *rqstp)
>>> return -EAGAIN;
>>> }
>>> len = svc_addr_len(svc_addr(rqstp));
>>> - if (len < 0)
>>> - return len;
>>> + if (len == 0)
>>> + return -EAFNOSUPPORT;
>>> rqstp->rq_addrlen = len;
>>> if (skb->tstamp.tv64 == 0) {
>>> skb->tstamp = ktime_get_real();
>>>
>
> --
> Chuck Lever
> chuck[dot]lever[at]oracle[dot]com
>
>
>
>
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