5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Anthony Iliopoulos ailiop@suse.com
[ Upstream commit 191512355e520dfc45c8bc3b56d4de59c3ade33e ]
When the client max_resp_sz is larger than what the server encodes in its reply, the nfs4_verify_back_channel_attrs() check fails and this causes nfs4_proc_create_session() to fail, in cases where the client page size is larger than that of the server and the server does not want to negotiate upwards.
While this is not a problem with the linux nfs server that will reflect the proposed value in its reply irrespective of the local page size, other nfs server implementations may insist on their own max_resp_sz value, which could be smaller.
Fix this by accepting smaller max_resp_sz values from the server, as this does not violate the protocol. The server is allowed to decrease but not increase proposed the size, and as such values smaller than the client-proposed ones are valid.
Fixes: 43c2e885be25 ("nfs4: fix channel attribute sanity-checks") Signed-off-by: Anthony Iliopoulos ailiop@suse.com Reviewed-by: Benjamin Coddington bcodding@redhat.com Signed-off-by: Anna Schumaker anna.schumaker@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/nfs/nfs4proc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index 3d854e2537bc2..a98b10c85b700 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -9117,7 +9117,7 @@ static int nfs4_verify_back_channel_attrs(struct nfs41_create_session_args *args goto out; if (rcvd->max_rqst_sz > sent->max_rqst_sz) return -EINVAL; - if (rcvd->max_resp_sz < sent->max_resp_sz) + if (rcvd->max_resp_sz > sent->max_resp_sz) return -EINVAL; if (rcvd->max_resp_sz_cached > sent->max_resp_sz_cached) return -EINVAL;