From: Hawkins Jiawei yin31149@gmail.com
[ Upstream commit 5559405df652008e56eee88872126fe4c451da67 ]
According to commit "vfs: parse: deal with zero length string value", kernel will set the param->string to null pointer in vfs_parse_fs_string() if fs string has zero length.
Yet the problem is that, nfs_fs_context_parse_param() will dereferences the param->string, without checking whether it is a null pointer, which may trigger a null-ptr-deref bug.
This patch solves it by adding sanity check on param->string in nfs_fs_context_parse_param().
Signed-off-by: Hawkins Jiawei yin31149@gmail.com Reviewed-by: Jeff Layton jlayton@kernel.org Signed-off-by: Trond Myklebust trond.myklebust@hammerspace.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/nfs/fs_context.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c index 4da701fd1424..0c330bc13ef2 100644 --- a/fs/nfs/fs_context.c +++ b/fs/nfs/fs_context.c @@ -684,6 +684,8 @@ static int nfs_fs_context_parse_param(struct fs_context *fc, return ret; break; case Opt_vers: + if (!param->string) + goto out_invalid_value; trace_nfs_mount_assign(param->key, param->string); ret = nfs_parse_version_string(fc, param->string); if (ret < 0) @@ -696,6 +698,8 @@ static int nfs_fs_context_parse_param(struct fs_context *fc, break;
case Opt_proto: + if (!param->string) + goto out_invalid_value; trace_nfs_mount_assign(param->key, param->string); protofamily = AF_INET; switch (lookup_constant(nfs_xprt_protocol_tokens, param->string, -1)) { @@ -732,6 +736,8 @@ static int nfs_fs_context_parse_param(struct fs_context *fc, break;
case Opt_mountproto: + if (!param->string) + goto out_invalid_value; trace_nfs_mount_assign(param->key, param->string); mountfamily = AF_INET; switch (lookup_constant(nfs_xprt_protocol_tokens, param->string, -1)) {