sunrpc: integer underflow in rsc_parse()

If we call groups_alloc() with invalid values then it's might lead to
memory corruption.  For example, with a negative value then we might not
allocate enough for sizeof(struct group_info).

(We're doing this in the caller for consistency with other callers of
groups_alloc().  The other alternative might be to move the check out of
all the callers into groups_alloc().)

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Simo Sorce <simo@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/net/sunrpc/auth_gss/svcauth_gss.c b/net/sunrpc/auth_gss/svcauth_gss.c
index 224a82f..1095be9 100644 (file)
--- a/net/sunrpc/auth_gss/svcauth_gss.c
+++ b/net/sunrpc/auth_gss/svcauth_gss.c
@@ -463,6 +463,8 @@ static int rsc_parse(struct cache_detail *cd,
                /* number of additional gid's */
                if (get_int(&mesg, &N))
                        goto out;
+               if (N < 0 || N > NGROUPS_MAX)
+                       goto out;
                status = -ENOMEM;
                rsci.cred.cr_group_info = groups_alloc(N);
                if (rsci.cred.cr_group_info == NULL)