From ce85cfbed6fe3dbc01bd1976b23ac3e97878cde6 Mon Sep 17 00:00:00 2001 From: Benjamin Coddington Date: Tue, 21 Apr 2015 14:17:35 -0400 Subject: [PATCH] NFS: Don't attempt to decode missing directory entries 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: [] 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 Signed-off-by: Trond Myklebust --- fs/nfs/dir.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index c19e16f0b2d0..a00ba92acccc 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -544,6 +544,9 @@ 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); @@ -565,6 +568,7 @@ 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)) { -- 2.34.1