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Subject[ 15/72] NFSv4: Fix an Oops in the NFSv4 getacl code
3.2-stable review patch.  If anyone has any objections, please let me know.

------------------
From: Trond Myklebust <Trond.Myklebust@netapp.com>

commit 331818f1c468a24e581aedcbe52af799366a9dfe upstream.

Commit bf118a342f10dafe44b14451a1392c3254629a1f (NFSv4: include bitmap
in nfsv4 get acl data) introduces the 'acl_scratch' page for the case
where we may need to decode multi-page data. However it fails to take
into account the fact that the variable may be NULL (for the case where
we're not doing multi-page decode), and it also attaches it to the
encoding xdr_stream rather than the decoding one.

The immediate result is an Oops in nfs4_xdr_enc_getacl due to the
call to page_address() with a NULL page pointer.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Andy Adamson <andros@netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/nfs/nfs4proc.c | 8 ++++----
fs/nfs/nfs4xdr.c | 5 ++++-
include/linux/nfs_xdr.h | 2 +-
3 files changed, 9 insertions(+), 6 deletions(-)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -3568,8 +3568,8 @@ static ssize_t __nfs4_get_acl_uncached(s
}
if (npages > 1) {
/* for decoding across pages */
- args.acl_scratch = alloc_page(GFP_KERNEL);
- if (!args.acl_scratch)
+ res.acl_scratch = alloc_page(GFP_KERNEL);
+ if (!res.acl_scratch)
goto out_free;
}
args.acl_len = npages * PAGE_SIZE;
@@ -3605,8 +3605,8 @@ out_free:
for (i = 0; i < npages; i++)
if (pages[i])
__free_page(pages[i]);
- if (args.acl_scratch)
- __free_page(args.acl_scratch);
+ if (res.acl_scratch)
+ __free_page(res.acl_scratch);
return ret;
}

--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -2522,7 +2522,6 @@ static void nfs4_xdr_enc_getacl(struct r

xdr_inline_pages(&req->rq_rcv_buf, replen << 2,
args->acl_pages, args->acl_pgbase, args->acl_len);
- xdr_set_scratch_buffer(xdr, page_address(args->acl_scratch), PAGE_SIZE);

encode_nops(&hdr);
}
@@ -6034,6 +6033,10 @@ nfs4_xdr_dec_getacl(struct rpc_rqst *rqs
struct compound_hdr hdr;
int status;

+ if (res->acl_scratch != NULL) {
+ void *p = page_address(res->acl_scratch);
+ xdr_set_scratch_buffer(xdr, p, PAGE_SIZE);
+ }
status = decode_compound_hdr(xdr, &hdr);
if (status)
goto out;
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -602,7 +602,6 @@ struct nfs_getaclargs {
size_t acl_len;
unsigned int acl_pgbase;
struct page ** acl_pages;
- struct page * acl_scratch;
struct nfs4_sequence_args seq_args;
};

@@ -612,6 +611,7 @@ struct nfs_getaclres {
size_t acl_len;
size_t acl_data_offset;
int acl_flags;
+ struct page * acl_scratch;
struct nfs4_sequence_res seq_res;
};




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