383143f31d
syzcaller reported the following use-after-free issue in rt6_select(): BUG: KASAN: use-after-free in rt6_select net/ipv6/route.c:755 [inline] at addr ffff8800bc6994e8 BUG: KASAN: use-after-free in ip6_pol_route.isra.46+0x1429/0x1470 net/ipv6/route.c:1084 at addr ffff8800bc6994e8 Read of size 4 by task syz-executor1/439628 CPU: 0 PID: 439628 Comm: syz-executor1 Not tainted 4.3.5+ #8 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 0000000000000000 ffff88018fe435b0 ffffffff81ca384d ffff8801d3588c00 ffff8800bc699380 ffff8800bc699500 dffffc0000000000 ffff8801d40a47c0 ffff88018fe435d8 ffffffff81735751 ffff88018fe43660 ffff8800bc699380 Call Trace: [<ffffffff81ca384d>] __dump_stack lib/dump_stack.c:15 [inline] [<ffffffff81ca384d>] dump_stack+0xc1/0x124 lib/dump_stack.c:51 sctp: [Deprecated]: syz-executor0 (pid 439615) Use of struct sctp_assoc_value in delayed_ack socket option. Use struct sctp_sack_info instead [<ffffffff81735751>] kasan_object_err+0x21/0x70 mm/kasan/report.c:158 [<ffffffff817359c4>] print_address_description mm/kasan/report.c:196 [inline] [<ffffffff817359c4>] kasan_report_error+0x1b4/0x4a0 mm/kasan/report.c:285 [<ffffffff81735d93>] kasan_report mm/kasan/report.c:305 [inline] [<ffffffff81735d93>] __asan_report_load4_noabort+0x43/0x50 mm/kasan/report.c:325 [<ffffffff82a28e39>] rt6_select net/ipv6/route.c:755 [inline] [<ffffffff82a28e39>] ip6_pol_route.isra.46+0x1429/0x1470 net/ipv6/route.c:1084 [<ffffffff82a28fb1>] ip6_pol_route_output+0x81/0xb0 net/ipv6/route.c:1203 [<ffffffff82ab0a50>] fib6_rule_action+0x1f0/0x680 net/ipv6/fib6_rules.c:95 [<ffffffff8265cbb6>] fib_rules_lookup+0x2a6/0x7a0 net/core/fib_rules.c:223 [<ffffffff82ab1430>] fib6_rule_lookup+0xd0/0x250 net/ipv6/fib6_rules.c:41 [<ffffffff82a22006>] ip6_route_output+0x1d6/0x2c0 net/ipv6/route.c:1224 [<ffffffff829e83d2>] ip6_dst_lookup_tail+0x4d2/0x890 net/ipv6/ip6_output.c:943 [<ffffffff829e889a>] ip6_dst_lookup_flow+0x9a/0x250 net/ipv6/ip6_output.c:1079 [<ffffffff82a9f7d8>] ip6_datagram_dst_update+0x538/0xd40 net/ipv6/datagram.c:91 [<ffffffff82aa0978>] __ip6_datagram_connect net/ipv6/datagram.c:251 [inline] [<ffffffff82aa0978>] ip6_datagram_connect+0x518/0xe50 net/ipv6/datagram.c:272 [<ffffffff82aa1313>] ip6_datagram_connect_v6_only+0x63/0x90 net/ipv6/datagram.c:284 [<ffffffff8292f790>] inet_dgram_connect+0x170/0x1f0 net/ipv4/af_inet.c:564 [<ffffffff82565547>] SYSC_connect+0x1a7/0x2f0 net/socket.c:1582 [<ffffffff8256a649>] SyS_connect+0x29/0x30 net/socket.c:1563 [<ffffffff82c72032>] entry_SYSCALL_64_fastpath+0x12/0x17 Object at ffff8800bc699380, in cache ip6_dst_cache size: 384 The root cause of it is that in fib6_add_rt2node(), when it replaces an existing route with the new one, it does not update fn->rr_ptr. This commit resets fn->rr_ptr to NULL when it points to a route which is replaced in fib6_add_rt2node(). Fixes: 27596472473a ("ipv6: fix ECMP route replacement") Signed-off-by: Wei Wang <weiwan@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.