4.4-stable review patch. If anyone has any objections, please let me know.
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From: Ying Xue ying.xue@windriver.com
commit edf5ff04a45750ac8ce2435974f001dc9cfbf055 upstream.
syzbot reports following splat:
BUG: KMSAN: uninit-value in strlen+0x3b/0xa0 lib/string.c:486 CPU: 1 PID: 9306 Comm: syz-executor172 Not tainted 4.20.0-rc7+ #2 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x173/0x1d0 lib/dump_stack.c:113 kmsan_report+0x12e/0x2a0 mm/kmsan/kmsan.c:613 __msan_warning+0x82/0xf0 mm/kmsan/kmsan_instr.c:313 strlen+0x3b/0xa0 lib/string.c:486 nla_put_string include/net/netlink.h:1154 [inline] __tipc_nl_compat_link_set net/tipc/netlink_compat.c:708 [inline] tipc_nl_compat_link_set+0x929/0x1220 net/tipc/netlink_compat.c:744 __tipc_nl_compat_doit net/tipc/netlink_compat.c:311 [inline] tipc_nl_compat_doit+0x3aa/0xaf0 net/tipc/netlink_compat.c:344 tipc_nl_compat_handle net/tipc/netlink_compat.c:1107 [inline] tipc_nl_compat_recv+0x14d7/0x2760 net/tipc/netlink_compat.c:1210 genl_family_rcv_msg net/netlink/genetlink.c:601 [inline] genl_rcv_msg+0x185f/0x1a60 net/netlink/genetlink.c:626 netlink_rcv_skb+0x444/0x640 net/netlink/af_netlink.c:2477 genl_rcv+0x63/0x80 net/netlink/genetlink.c:637 netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline] netlink_unicast+0xf40/0x1020 net/netlink/af_netlink.c:1336 netlink_sendmsg+0x127f/0x1300 net/netlink/af_netlink.c:1917 sock_sendmsg_nosec net/socket.c:621 [inline] sock_sendmsg net/socket.c:631 [inline] ___sys_sendmsg+0xdb9/0x11b0 net/socket.c:2116 __sys_sendmsg net/socket.c:2154 [inline] __do_sys_sendmsg net/socket.c:2163 [inline] __se_sys_sendmsg+0x305/0x460 net/socket.c:2161 __x64_sys_sendmsg+0x4a/0x70 net/socket.c:2161 do_syscall_64+0xbc/0xf0 arch/x86/entry/common.c:291 entry_SYSCALL_64_after_hwframe+0x63/0xe7
The uninitialised access happened in nla_put_string(skb, TIPC_NLA_LINK_NAME, lc->name)
This is because lc->name string is not validated before it's used.
Reported-by: syzbot+d78b8a29241a195aefb8@syzkaller.appspotmail.com Signed-off-by: Ying Xue ying.xue@windriver.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/tipc/netlink_compat.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/net/tipc/netlink_compat.c +++ b/net/tipc/netlink_compat.c @@ -723,9 +723,14 @@ static int tipc_nl_compat_link_set(struc struct tipc_link_config *lc; struct tipc_bearer *bearer; struct tipc_media *media; + int len;
lc = (struct tipc_link_config *)TLV_DATA(msg->req);
+ len = min_t(int, TLV_GET_DATA_LEN(msg->req), TIPC_MAX_LINK_NAME); + if (!string_is_valid(lc->name, len)) + return -EINVAL; + media = tipc_media_find(lc->name); if (media) { cmd->doit = &tipc_nl_media_set;