From: Benjamin Coddington <bcodding@xxxxxxxxxx>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
commit ce85cfbed6fe3dbc01bd1976b23ac3e97878cde6 upstream.
If a READDIR reply comes back without any page data, avoid a NULL pointer
dereference in xdr_copy_to_scratch().
BUG: unable to handle kernel NULL pointer dereference at 0000000000000001
IP: [<ffffffff813a378d>] memcpy+0xd/0x110
...
Call Trace:
? xdr_inline_decode+0x7a/0xb0 [sunrpc]
nfs3_decode_dirent+0x73/0x320 [nfsv3]
nfs_readdir_page_filler+0xd5/0x4e0 [nfs]
? nfs3_rpc_wrapper.constprop.9+0x42/0xc0 [nfsv3]
nfs_readdir_xdr_to_array+0x1fa/0x330 [nfs]
? mem_cgroup_commit_charge+0xac/0x160
? nfs_readdir_xdr_to_array+0x330/0x330 [nfs]
nfs_readdir_filler+0x22/0x90 [nfs]
do_read_cache_page+0x7e/0x1a0
read_cache_page+0x1c/0x20
nfs_readdir+0x18e/0x660 [nfs]
? nfs3_xdr_dec_getattr3res+0x80/0x80 [nfsv3]
iterate_dir+0x97/0x130
SyS_getdents+0x94/0x120
? fillonedir+0xd0/0xd0
system_call_fastpath+0x12/0x17
Signed-off-by: Benjamin Coddington <bcodding@xxxxxxxxxx>
Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Cc: Neil Brown <nfbrown@xxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
fs/nfs/dir.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 140280623348..cf6ede69a2e2 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -510,6 +510,9 @@ int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *en
if (scratch == NULL)
return -ENOMEM;
+ if (buflen == 0)
+ goto out_nopages;
+
xdr_init_decode_pages(&stream, &buf, xdr_pages, buflen);
xdr_set_scratch_buffer(&stream, page_address(scratch), PAGE_SIZE);
@@ -531,6 +534,7 @@ int nfs_readdir_page_filler(nfs_readdir_descriptor_t *desc, struct nfs_entry *en
break;
} while (!entry->eof);
+out_nopages:
if (count == 0 || (status == -EBADCOOKIE && entry->eof != 0)) {
array = nfs_readdir_get_array(page);
if (!IS_ERR(array)) {
--
2.9.0
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