From 9d3a2260f0f4bd6379b0a0f131c743fff25b0029 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Mon, 28 Oct 2013 18:18:00 -0400 Subject: [PATCH] SUNRPC: Fix buffer overflow checking in gss_encode_v0_msg/gss_encode_v1_msg In gss_encode_v1_msg, it is pointless to BUG() after the overflow has happened. Replace the existing sprintf()-based code with scnprintf(), and warn if an overflow is ever triggered. In gss_encode_v0_msg, replace the runtime BUG_ON() with an appropriate compile-time BUILD_BUG_ON. Reported-by: Bruce Fields Signed-off-by: Trond Myklebust --- net/sunrpc/auth_gss/auth_gss.c | 56 ++++++++++++++++++++++------------ 1 file changed, 37 insertions(+), 19 deletions(-) diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c index cc24323d3045..97912b40c254 100644 --- a/net/sunrpc/auth_gss/auth_gss.c +++ b/net/sunrpc/auth_gss/auth_gss.c @@ -420,41 +420,53 @@ static void gss_encode_v0_msg(struct gss_upcall_msg *gss_msg) memcpy(gss_msg->databuf, &uid, sizeof(uid)); gss_msg->msg.data = gss_msg->databuf; gss_msg->msg.len = sizeof(uid); - BUG_ON(sizeof(uid) > UPCALL_BUF_LEN); + + BUILD_BUG_ON(sizeof(uid) > sizeof(gss_msg->databuf)); } -static void gss_encode_v1_msg(struct gss_upcall_msg *gss_msg, +static int gss_encode_v1_msg(struct gss_upcall_msg *gss_msg, const char *service_name, const char *target_name) { struct gss_api_mech *mech = gss_msg->auth->mech; char *p = gss_msg->databuf; - int len = 0; - - gss_msg->msg.len = sprintf(gss_msg->databuf, "mech=%s uid=%d ", - mech->gm_name, - from_kuid(&init_user_ns, gss_msg->uid)); - p += gss_msg->msg.len; + size_t buflen = sizeof(gss_msg->databuf); + int len; + + len = scnprintf(p, buflen, "mech=%s uid=%d ", mech->gm_name, + from_kuid(&init_user_ns, gss_msg->uid)); + buflen -= len; + p += len; + gss_msg->msg.len = len; if (target_name) { - len = sprintf(p, "target=%s ", target_name); + len = scnprintf(p, buflen, "target=%s ", target_name); + buflen -= len; p += len; gss_msg->msg.len += len; } if (service_name != NULL) { - len = sprintf(p, "service=%s ", service_name); + len = scnprintf(p, buflen, "service=%s ", service_name); + buflen -= len; p += len; gss_msg->msg.len += len; } if (mech->gm_upcall_enctypes) { - len = sprintf(p, "enctypes=%s ", mech->gm_upcall_enctypes); + len = scnprintf(p, buflen, "enctypes=%s ", + mech->gm_upcall_enctypes); + buflen -= len; p += len; gss_msg->msg.len += len; } - len = sprintf(p, "\n"); + len = scnprintf(p, buflen, "\n"); + if (len == 0) + goto out_overflow; gss_msg->msg.len += len; gss_msg->msg.data = gss_msg->databuf; - BUG_ON(gss_msg->msg.len > UPCALL_BUF_LEN); + return 0; +out_overflow: + WARN_ON_ONCE(1); + return -ENOMEM; } static struct gss_upcall_msg * @@ -463,15 +475,15 @@ gss_alloc_msg(struct gss_auth *gss_auth, { struct gss_upcall_msg *gss_msg; int vers; + int err = -ENOMEM; gss_msg = kzalloc(sizeof(*gss_msg), GFP_NOFS); if (gss_msg == NULL) - return ERR_PTR(-ENOMEM); + goto err; vers = get_pipe_version(gss_auth->net); - if (vers < 0) { - kfree(gss_msg); - return ERR_PTR(vers); - } + err = vers; + if (err < 0) + goto err_free_msg; gss_msg->pipe = gss_auth->gss_pipe[vers]->pipe; INIT_LIST_HEAD(&gss_msg->list); rpc_init_wait_queue(&gss_msg->rpc_waitqueue, "RPCSEC_GSS upcall waitq"); @@ -484,9 +496,15 @@ gss_alloc_msg(struct gss_auth *gss_auth, gss_encode_v0_msg(gss_msg); break; default: - gss_encode_v1_msg(gss_msg, service_name, gss_auth->target_name); + err = gss_encode_v1_msg(gss_msg, service_name, gss_auth->target_name); + if (err) + goto err_free_msg; }; return gss_msg; +err_free_msg: + kfree(gss_msg); +err: + return ERR_PTR(err); } static struct gss_upcall_msg * -- 2.20.1