From c3dfc2808ab82b13f8b6db62189da959c2eadeea Mon Sep 17 00:00:00 2001 From: Bryan Schumaker Date: Wed, 13 Apr 2011 14:31:31 -0400 Subject: [PATCH] NFS: Use correct variable for page bounds checking While decoding a secinfo reply, I store the list of supported sec flavors on a page accessible through res->flavors. Before reading each new flavor, I do some math to determine if there is enough space left on this page, and I break out of my read look if there isn't. In order to perform this check correctly, I need to use the address of res->flavors, rather than the address of res. When this loop was broken early I lied to the caller and told them that the entire list had been decoded. This could lead to problems if the caller tries to use any the garbage data claiming to be a valid sec flavor. I fixed this by using res->flavors->num_flavors as a counter, incrementing it every time a sec flavor is successfully decoded. Signed-off-by: Bryan Schumaker Signed-off-by: Trond Myklebust --- fs/nfs/nfs4xdr.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c index dddfb5795d7b..ba952bdc4d62 100644 --- a/fs/nfs/nfs4xdr.c +++ b/fs/nfs/nfs4xdr.c @@ -4838,17 +4838,19 @@ static int decode_secinfo(struct xdr_stream *xdr, struct nfs4_secinfo_res *res) struct nfs4_secinfo_flavor *sec_flavor; int status; __be32 *p; - int i; + int i, num_flavors; status = decode_op_hdr(xdr, OP_SECINFO); p = xdr_inline_decode(xdr, 4); if (unlikely(!p)) goto out_overflow; - res->flavors->num_flavors = be32_to_cpup(p); - for (i = 0; i < res->flavors->num_flavors; i++) { + res->flavors->num_flavors = 0; + num_flavors = be32_to_cpup(p); + + for (i = 0; i < num_flavors; i++) { sec_flavor = &res->flavors->flavors[i]; - if ((char *)&sec_flavor[1] - (char *)res > PAGE_SIZE) + if ((char *)&sec_flavor[1] - (char *)res->flavors > PAGE_SIZE) break; p = xdr_inline_decode(xdr, 4); @@ -4860,6 +4862,7 @@ static int decode_secinfo(struct xdr_stream *xdr, struct nfs4_secinfo_res *res) if (decode_secinfo_gss(xdr, sec_flavor)) break; } + res->flavors->num_flavors++; } return 0; -- 2.34.1