netdev - [PATCH net] team: better TEAM_OPTION_TYPE

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Message-ID: <20250212134928.1541609-1-edumazet@google.com>
Date: Wed, 12 Feb 2025 13:49:28 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, Simon Horman <horms@...nel.org>, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>, syzbot+1fcd957a82e3a1baa94d@...kaller.appspotmail.com, 
	Jiri Pirko <jiri@...dia.com>
Subject: [PATCH net] team: better TEAM_OPTION_TYPE_STRING validation

syzbot reported following splat [1]

Make sure user-provided data contains one nul byte.

[1]
 BUG: KMSAN: uninit-value in string_nocheck lib/vsprintf.c:633 [inline]
 BUG: KMSAN: uninit-value in string+0x3ec/0x5f0 lib/vsprintf.c:714
  string_nocheck lib/vsprintf.c:633 [inline]
  string+0x3ec/0x5f0 lib/vsprintf.c:714
  vsnprintf+0xa5d/0x1960 lib/vsprintf.c:2843
  __request_module+0x252/0x9f0 kernel/module/kmod.c:149
  team_mode_get drivers/net/team/team_core.c:480 [inline]
  team_change_mode drivers/net/team/team_core.c:607 [inline]
  team_mode_option_set+0x437/0x970 drivers/net/team/team_core.c:1401
  team_option_set drivers/net/team/team_core.c:375 [inline]
  team_nl_options_set_doit+0x1339/0x1f90 drivers/net/team/team_core.c:2662
  genl_family_rcv_msg_doit net/netlink/genetlink.c:1115 [inline]
  genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
  genl_rcv_msg+0x1214/0x12c0 net/netlink/genetlink.c:1210
  netlink_rcv_skb+0x375/0x650 net/netlink/af_netlink.c:2543
  genl_rcv+0x40/0x60 net/netlink/genetlink.c:1219
  netlink_unicast_kernel net/netlink/af_netlink.c:1322 [inline]
  netlink_unicast+0xf52/0x1260 net/netlink/af_netlink.c:1348
  netlink_sendmsg+0x10da/0x11e0 net/netlink/af_netlink.c:1892
  sock_sendmsg_nosec net/socket.c:718 [inline]
  __sock_sendmsg+0x30f/0x380 net/socket.c:733
  ____sys_sendmsg+0x877/0xb60 net/socket.c:2573
  ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2627
  __sys_sendmsg net/socket.c:2659 [inline]
  __do_sys_sendmsg net/socket.c:2664 [inline]
  __se_sys_sendmsg net/socket.c:2662 [inline]
  __x64_sys_sendmsg+0x212/0x3c0 net/socket.c:2662
  x64_sys_call+0x2ed6/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:47
  do_syscall_x64 arch/x86/entry/common.c:52 [inline]
  do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Fixes: 3d249d4ca7d0 ("net: introduce ethernet teaming device")
Reported-by: syzbot+1fcd957a82e3a1baa94d@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=1fcd957a82e3a1baa94d
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Jiri Pirko <jiri@...dia.com>
---
 drivers/net/team/team_core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/team/team_core.c b/drivers/net/team/team_core.c
index dc7cbd6a9798a7b09422c0bb1bf38b74dc113b1e..f4019815f473617708b4e0662b355c7738c64731 100644
--- a/drivers/net/team/team_core.c
+++ b/drivers/net/team/team_core.c
@@ -2639,7 +2639,9 @@ int team_nl_options_set_doit(struct sk_buff *skb, struct genl_info *info)
 				ctx.data.u32_val = nla_get_u32(attr_data);
 				break;
 			case TEAM_OPTION_TYPE_STRING:
-				if (nla_len(attr_data) > TEAM_STRING_MAX_LEN) {
+				if (nla_len(attr_data) > TEAM_STRING_MAX_LEN ||
+				    !memchr(nla_data(attr_data), '\0',
+					    nla_len(attr_data))) {
 					err = -EINVAL;
 					goto team_put;
 				}
-- 
2.48.1.502.g6dc24dfdaf-goog