| Re: [PATCH] [RFC] nfsd: fix possible dereference of static NULL nfsd_serv pointer [message #47106 is a reply to message #47104] |
Sat, 07 July 2012 05:27   |
Stanislav Kinsbursky
Messages: 683
Registered: October 2011
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Senior Member |
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06.07.2012 21:26, J. Bruce Fields пишет:
> On Fri, Jul 06, 2012 at 05:45:56PM +0400, Stanislav Kinsbursky wrote:
>> This is a bug fix for 3.5 kernel.
>> In case on NFSd service start failure svc_shutdown_net() will call svc_destroy
>> callback and zeroize global nfsd_serv pointer, this in turn will lead to Oops
>> in svc_destroy().
>>
>> This patch is marked as RFC, because to many lines were changed. It can be
>> easely simplified if requested.
>> Moreover, NFSd service shutdown is going to be converted into csomething on
>> per-net basis.
> Doesn't this leave error paths in e.g. __write_ports_addfd() and
> __write_ports_addxprt() unfixed?
Yes, sure it does...
> I'm inclined to just submit your original fix (split up as in the last
> version I sent) for 3.5 if you don't object.
Not at all.
Thanks, Bruce.
> --b.
>
>> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
>> ---
>> fs/nfsd/nfssvc.c | 14 ++++++++------
>> 1 files changed, 8 insertions(+), 6 deletions(-)
>>
>> diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
>> index ee709fc..526a4aa 100644
>> --- a/fs/nfsd/nfssvc.c
>> +++ b/fs/nfsd/nfssvc.c
>> @@ -446,6 +446,7 @@ nfsd_svc(unsigned short port, int nrservs)
>> int error;
>> bool nfsd_up_before;
>> struct net *net = &init_net;
>> + struct svc_serv *serv = nfsd_serv;
>>
>> mutex_lock(&nfsd_mutex);
>> dprintk("nfsd: creating service\n");
>> @@ -454,7 +455,7 @@ nfsd_svc(unsigned short port, int nrservs)
>> if (nrservs > NFSD_MAXSERVS)
>> nrservs = NFSD_MAXSERVS;
>> error = 0;
>> - if (nrservs == 0 && nfsd_serv == NULL)
>> + if (nrservs == 0 && serv == NULL)
>> goto out;
>>
>> error = nfsd_create_serv();
>> @@ -464,23 +465,24 @@ nfsd_svc(unsigned short port, int nrservs)
>> nfsd_up_before = nfsd_up;
>>
>> error = nfsd_startup(port, nrservs);
>> + error = -EINVAL;
>> if (error)
>> goto out_destroy;
>> - error = svc_set_num_threads(nfsd_serv, NULL, nrservs);
>> + error = svc_set_num_threads(serv, NULL, nrservs);
>> if (error)
>> goto out_shutdown;
>> /* We are holding a reference to nfsd_serv which
>> * we don't want to count in the return value,
>> * so subtract 1
>> */
>> - error = nfsd_serv->sv_nrthreads - 1;
>> + error = serv->sv_nrthreads - 1;
>> out_shutdown:
>> if (error < 0 && !nfsd_up_before)
>> nfsd_shutdown();
>> out_destroy:
>> - if (nfsd_serv->sv_nrthreads == 1)
>> - svc_shutdown_net(nfsd_serv, net);
>> - svc_destroy(nfsd_serv); /* Release server */
>> + if (serv->sv_nrthreads == 1)
>> + svc_shutdown_net(serv, net);
>> + svc_destroy(serv); /* Release server */
>> out:
>> mutex_unlock(&nfsd_mutex);
>> return error;
>>
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