From cd123012d99fde4759500fee611e724e4f3016e3 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Wed, 9 May 2007 02:34:50 -0700 Subject: RPC: add wrapper for svc_reserve to account for checksum When the kernel calls svc_reserve to downsize the expected size of an RPC reply, it fails to account for the possibility of a checksum at the end of the packet. If a client mounts a NFSv2/3 with sec=krb5i/p, and does I/O then you'll generally see messages similar to this in the server's ring buffer: RPC request reserved 164 but used 208 While I was never able to verify it, I suspect that this problem is also the root cause of some oopses I've seen under these conditions: https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=227726 This is probably also a problem for other sec= types and for NFSv4. The large reserved size for NFSv4 compound packets seems to generally paper over the problem, however. This patch adds a wrapper for svc_reserve that accounts for the possibility of a checksum. It also fixes up the appropriate callers of svc_reserve to call the wrapper. For now, it just uses a hardcoded value that I determined via testing. That value may need to be revised upward as things change, or we may want to eventually add a new auth_op that attempts to calculate this somehow. Unfortunately, there doesn't seem to be a good way to reliably determine the expected checksum length prior to actually calculating it, particularly with schemes like spkm3. Signed-off-by: Jeff Layton Acked-by: Neil Brown Cc: Trond Myklebust Acked-by: J. Bruce Fields Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- net/sunrpc/svc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/sunrpc') diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c index b7503c103ae..e673ef99390 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -907,7 +907,7 @@ svc_process(struct svc_rqst *rqstp) * better idea of reply size */ if (procp->pc_xdrressize) - svc_reserve(rqstp, procp->pc_xdrressize<<2); + svc_reserve_auth(rqstp, procp->pc_xdrressize<<2); /* Call the function that processes the request. */ if (!versp->vs_dispatch) { -- cgit v1.2.3