[PATCH] nfsd: don't modify group_info structures

From: Neil Brown <neilb@cse.unsw.edu.au>

Make sure nfsd doesn't modify group_info structures as they might be
shared.

diff --git a/fs/nfsd/auth.c b/fs/nfsd/auth.c
index bf38d343a285f942fb63fbd9810b18d72ad88fef..cfe9ce8816132373791a60e8be6e2ed1ed92f064 100644 (file)
--- a/fs/nfsd/auth.c
+++ b/fs/nfsd/auth.c
@@ -21,15 +21,24 @@ int nfsd_setuser(struct svc_rqst *rqstp, struct svc_export *exp)
        if (exp->ex_flags & NFSEXP_ALLSQUASH) {
                cred->cr_uid = exp->ex_anon_uid;
                cred->cr_gid = exp->ex_anon_gid;
-               cred->cr_group_info->ngroups = 0;
+               put_group_info(cred->cr_group_info);
+               cred->cr_group_info = groups_alloc(0);
        } else if (exp->ex_flags & NFSEXP_ROOTSQUASH) {
+               struct group_info *gi;
                if (!cred->cr_uid)
                        cred->cr_uid = exp->ex_anon_uid;
                if (!cred->cr_gid)
                        cred->cr_gid = exp->ex_anon_gid;
-               for (i = 0; i < cred->cr_group_info->ngroups; i++)
-                       if (!GROUP_AT(cred->cr_group_info, i))
-                               GROUP_AT(cred->cr_group_info, i) = exp->ex_anon_gid;
+               gi = groups_alloc(cred->cr_group_info->ngroups);
+               if (gi)
+                       for (i = 0; i < cred->cr_group_info->ngroups; i++) {
+                               if (!GROUP_AT(cred->cr_group_info, i))
+                                       GROUP_AT(gi, i) = exp->ex_anon_gid;
+                               else
+                                       GROUP_AT(gi, i) = GROUP_AT(cred->cr_group_info, i);
+                       }
+               put_group_info(cred->cr_group_info);
+               cred->cr_group_info = gi;
        }
 
        if (cred->cr_uid != (uid_t) -1)
@@ -41,6 +50,8 @@ int nfsd_setuser(struct svc_rqst *rqstp, struct svc_export *exp)
        else
                current->fsgid = exp->ex_anon_gid;
 
+       if (!cred->cr_group_info)
+               return -ENOMEM;
        ret = set_current_groups(cred->cr_group_info);
        if ((cred->cr_uid)) {
                cap_t(current->cap_effective) &= ~CAP_NFSD_MASK;