4.4-stable review patch. If anyone has any objections, please let me know.
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From: Xin Long lucien.xin@gmail.com
[ Upstream commit 4a2eb0c37b4759416996fbb4c45b932500cf06d3 ]
syzbot reported a kernel-infoleak, which is caused by an uninitialized field(sin6_flowinfo) of addr->a.v6 in sctp_inet6addr_event(). The call trace is as below:
BUG: KMSAN: kernel-infoleak in _copy_to_user+0x19a/0x230 lib/usercopy.c:33 CPU: 1 PID: 8164 Comm: syz-executor2 Not tainted 4.20.0-rc3+ #95 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+0x32d/0x480 lib/dump_stack.c:113 kmsan_report+0x12c/0x290 mm/kmsan/kmsan.c:683 kmsan_internal_check_memory+0x32a/0xa50 mm/kmsan/kmsan.c:743 kmsan_copy_to_user+0x78/0xd0 mm/kmsan/kmsan_hooks.c:634 _copy_to_user+0x19a/0x230 lib/usercopy.c:33 copy_to_user include/linux/uaccess.h:183 [inline] sctp_getsockopt_local_addrs net/sctp/socket.c:5998 [inline] sctp_getsockopt+0x15248/0x186f0 net/sctp/socket.c:7477 sock_common_getsockopt+0x13f/0x180 net/core/sock.c:2937 __sys_getsockopt+0x489/0x550 net/socket.c:1939 __do_sys_getsockopt net/socket.c:1950 [inline] __se_sys_getsockopt+0xe1/0x100 net/socket.c:1947 __x64_sys_getsockopt+0x62/0x80 net/socket.c:1947 do_syscall_64+0xcf/0x110 arch/x86/entry/common.c:291 entry_SYSCALL_64_after_hwframe+0x63/0xe7
sin6_flowinfo is not really used by SCTP, so it will be fixed by simply setting it to 0.
The issue exists since very beginning. Thanks Alexander for the reproducer provided.
Reported-by: syzbot+ad5d327e6936a2e284be@syzkaller.appspotmail.com Signed-off-by: Xin Long lucien.xin@gmail.com Acked-by: Marcelo Ricardo Leitner marcelo.leitner@gmail.com Acked-by: Neil Horman nhorman@tuxdriver.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sctp/ipv6.c | 1 + 1 file changed, 1 insertion(+)
--- a/net/sctp/ipv6.c +++ b/net/sctp/ipv6.c @@ -101,6 +101,7 @@ static int sctp_inet6addr_event(struct n if (addr) { addr->a.v6.sin6_family = AF_INET6; addr->a.v6.sin6_port = 0; + addr->a.v6.sin6_flowinfo = 0; addr->a.v6.sin6_addr = ifa->addr; addr->a.v6.sin6_scope_id = ifa->idev->dev->ifindex; addr->valid = 1;