5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Trond Myklebust trond.myklebust@hammerspace.com
[ Upstream commit ef93a685e01a281b5e2a25ce4e3428cf9371a205 ]
The function needs to check the minimal filehandle length before it can access the embedded filehandle.
Reported-by: zhangjian zhangjian496@huawei.com Fixes: 20fa19027286 ("nfs: add export operations") Signed-off-by: Trond Myklebust trond.myklebust@hammerspace.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/nfs/export.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/fs/nfs/export.c b/fs/nfs/export.c index deecb67638aa..97b6fa0adb57 100644 --- a/fs/nfs/export.c +++ b/fs/nfs/export.c @@ -67,14 +67,21 @@ nfs_fh_to_dentry(struct super_block *sb, struct fid *fid, struct nfs4_label *label = NULL; struct nfs_fattr *fattr = NULL; struct nfs_fh *server_fh = nfs_exp_embedfh(fid->raw); - size_t fh_size = offsetof(struct nfs_fh, data) + server_fh->size; + size_t fh_size = offsetof(struct nfs_fh, data); const struct nfs_rpc_ops *rpc_ops; struct dentry *dentry; struct inode *inode; - int len = EMBED_FH_OFF + XDR_QUADLEN(fh_size); + int len = EMBED_FH_OFF; u32 *p = fid->raw; int ret;
+ /* Initial check of bounds */ + if (fh_len < len + XDR_QUADLEN(fh_size) || + fh_len > XDR_QUADLEN(NFS_MAXFHSIZE)) + return NULL; + /* Calculate embedded filehandle size */ + fh_size += server_fh->size; + len += XDR_QUADLEN(fh_size); /* NULL translates to ESTALE */ if (fh_len < len || fh_type != len) return NULL;