This is a note to let you know that I've just added the patch titled
sctp: Avoid out-of-bounds reads from address storage
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sctp-avoid-out-of-bounds-reads-from-address-storage.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Sep 14 23:20:08 PDT 2017
From: Stefano Brivio <sbrivio@xxxxxxxxxx>
Date: Wed, 23 Aug 2017 13:27:13 +0200
Subject: sctp: Avoid out-of-bounds reads from address storage
From: Stefano Brivio <sbrivio@xxxxxxxxxx>
[ Upstream commit ee6c88bb754e3d363e568da78086adfedb692447 ]
inet_diag_msg_sctp{,l}addr_fill() and sctp_get_sctp_info() copy
sizeof(sockaddr_storage) bytes to fill in sockaddr structs used
to export diagnostic information to userspace.
However, the memory allocated to store sockaddr information is
smaller than that and depends on the address family, so we leak
up to 100 uninitialized bytes to userspace. Just use the size of
the source structs instead, in all the three cases this is what
userspace expects. Zero out the remaining memory.
Unused bytes (i.e. when IPv4 addresses are used) in source
structs sctp_sockaddr_entry and sctp_transport are already
cleared by sctp_add_bind_addr() and sctp_transport_new(),
respectively.
Noticed while testing KASAN-enabled kernel with 'ss':
[ 2326.885243] BUG: KASAN: slab-out-of-bounds in inet_sctp_diag_fill+0x42c/0x6c0 [sctp_diag] at addr ffff881be8779800
[ 2326.896800] Read of size 128 by task ss/9527
[ 2326.901564] CPU: 0 PID: 9527 Comm: ss Not tainted 4.11.0-22.el7a.x86_64 #1
[ 2326.909236] Hardware name: Dell Inc. PowerEdge R730/072T6D, BIOS 2.4.3 01/17/2017
[ 2326.917585] Call Trace:
[ 2326.920312] dump_stack+0x63/0x8d
[ 2326.924014] kasan_object_err+0x21/0x70
[ 2326.928295] kasan_report+0x288/0x540
[ 2326.932380] ? inet_sctp_diag_fill+0x42c/0x6c0 [sctp_diag]
[ 2326.938500] ? skb_put+0x8b/0xd0
[ 2326.942098] ? memset+0x31/0x40
[ 2326.945599] check_memory_region+0x13c/0x1a0
[ 2326.950362] memcpy+0x23/0x50
[ 2326.953669] inet_sctp_diag_fill+0x42c/0x6c0 [sctp_diag]
[ 2326.959596] ? inet_diag_msg_sctpasoc_fill+0x460/0x460 [sctp_diag]
[ 2326.966495] ? __lock_sock+0x102/0x150
[ 2326.970671] ? sock_def_wakeup+0x60/0x60
[ 2326.975048] ? remove_wait_queue+0xc0/0xc0
[ 2326.979619] sctp_diag_dump+0x44a/0x760 [sctp_diag]
[ 2326.985063] ? sctp_ep_dump+0x280/0x280 [sctp_diag]
[ 2326.990504] ? memset+0x31/0x40
[ 2326.994007] ? mutex_lock+0x12/0x40
[ 2326.997900] __inet_diag_dump+0x57/0xb0 [inet_diag]
[ 2327.003340] ? __sys_sendmsg+0x150/0x150
[ 2327.007715] inet_diag_dump+0x4d/0x80 [inet_diag]
[ 2327.012979] netlink_dump+0x1e6/0x490
[ 2327.017064] __netlink_dump_start+0x28e/0x2c0
[ 2327.021924] inet_diag_handler_cmd+0x189/0x1a0 [inet_diag]
[ 2327.028045] ? inet_diag_rcv_msg_compat+0x1b0/0x1b0 [inet_diag]
[ 2327.034651] ? inet_diag_dump_compat+0x190/0x190 [inet_diag]
[ 2327.040965] ? __netlink_lookup+0x1b9/0x260
[ 2327.045631] sock_diag_rcv_msg+0x18b/0x1e0
[ 2327.050199] netlink_rcv_skb+0x14b/0x180
[ 2327.054574] ? sock_diag_bind+0x60/0x60
[ 2327.058850] sock_diag_rcv+0x28/0x40
[ 2327.062837] netlink_unicast+0x2e7/0x3b0
[ 2327.067212] ? netlink_attachskb+0x330/0x330
[ 2327.071975] ? kasan_check_write+0x14/0x20
[ 2327.076544] netlink_sendmsg+0x5be/0x730
[ 2327.080918] ? netlink_unicast+0x3b0/0x3b0
[ 2327.085486] ? kasan_check_write+0x14/0x20
[ 2327.090057] ? selinux_socket_sendmsg+0x24/0x30
[ 2327.095109] ? netlink_unicast+0x3b0/0x3b0
[ 2327.099678] sock_sendmsg+0x74/0x80
[ 2327.103567] ___sys_sendmsg+0x520/0x530
[ 2327.107844] ? __get_locked_pte+0x178/0x200
[ 2327.112510] ? copy_msghdr_from_user+0x270/0x270
[ 2327.117660] ? vm_insert_page+0x360/0x360
[ 2327.122133] ? vm_insert_pfn_prot+0xb4/0x150
[ 2327.126895] ? vm_insert_pfn+0x32/0x40
[ 2327.131077] ? vvar_fault+0x71/0xd0
[ 2327.134968] ? special_mapping_fault+0x69/0x110
[ 2327.140022] ? __do_fault+0x42/0x120
[ 2327.144008] ? __handle_mm_fault+0x1062/0x17a0
[ 2327.148965] ? __fget_light+0xa7/0xc0
[ 2327.153049] __sys_sendmsg+0xcb/0x150
[ 2327.157133] ? __sys_sendmsg+0xcb/0x150
[ 2327.161409] ? SyS_shutdown+0x140/0x140
[ 2327.165688] ? exit_to_usermode_loop+0xd0/0xd0
[ 2327.170646] ? __do_page_fault+0x55d/0x620
[ 2327.175216] ? __sys_sendmsg+0x150/0x150
[ 2327.179591] SyS_sendmsg+0x12/0x20
[ 2327.183384] do_syscall_64+0xe3/0x230
[ 2327.187471] entry_SYSCALL64_slow_path+0x25/0x25
[ 2327.192622] RIP: 0033:0x7f41d18fa3b0
[ 2327.196608] RSP: 002b:00007ffc3b731218 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
[ 2327.205055] RAX: ffffffffffffffda RBX: 00007ffc3b731380 RCX: 00007f41d18fa3b0
[ 2327.213017] RDX: 0000000000000000 RSI: 00007ffc3b731340 RDI: 0000000000000003
[ 2327.220978] RBP: 0000000000000002 R08: 0000000000000004 R09: 0000000000000040
[ 2327.228939] R10: 00007ffc3b730f30 R11: 0000000000000246 R12: 0000000000000003
[ 2327.236901] R13: 00007ffc3b731340 R14: 00007ffc3b7313d0 R15: 0000000000000084
[ 2327.244865] Object at ffff881be87797e0, in cache kmalloc-64 size: 64
[ 2327.251953] Allocated:
[ 2327.254581] PID = 9484
[ 2327.257215] save_stack_trace+0x1b/0x20
[ 2327.261485] save_stack+0x46/0xd0
[ 2327.265179] kasan_kmalloc+0xad/0xe0
[ 2327.269165] kmem_cache_alloc_trace+0xe6/0x1d0
[ 2327.274138] sctp_add_bind_addr+0x58/0x180 [sctp]
[ 2327.279400] sctp_do_bind+0x208/0x310 [sctp]
[ 2327.284176] sctp_bind+0x61/0xa0 [sctp]
[ 2327.288455] inet_bind+0x5f/0x3a0
[ 2327.292151] SYSC_bind+0x1a4/0x1e0
[ 2327.295944] SyS_bind+0xe/0x10
[ 2327.299349] do_syscall_64+0xe3/0x230
[ 2327.303433] return_from_SYSCALL_64+0x0/0x6a
[ 2327.308194] Freed:
[ 2327.310434] PID = 4131
[ 2327.313065] save_stack_trace+0x1b/0x20
[ 2327.317344] save_stack+0x46/0xd0
[ 2327.321040] kasan_slab_free+0x73/0xc0
[ 2327.325220] kfree+0x96/0x1a0
[ 2327.328530] dynamic_kobj_release+0x15/0x40
[ 2327.333195] kobject_release+0x99/0x1e0
[ 2327.337472] kobject_put+0x38/0x70
[ 2327.341266] free_notes_attrs+0x66/0x80
[ 2327.345545] mod_sysfs_teardown+0x1a5/0x270
[ 2327.350211] free_module+0x20/0x2a0
[ 2327.354099] SyS_delete_module+0x2cb/0x2f0
[ 2327.358667] do_syscall_64+0xe3/0x230
[ 2327.362750] return_from_SYSCALL_64+0x0/0x6a
[ 2327.367510] Memory state around the buggy address:
[ 2327.372855] ffff881be8779700: fc fc fc fc 00 00 00 00 00 00 00 00 fc fc fc fc
[ 2327.380914] ffff881be8779780: fb fb fb fb fb fb fb fb fc fc fc fc 00 00 00 00
[ 2327.388972] >ffff881be8779800: 00 00 00 00 fc fc fc fc fb fb fb fb fb fb fb fb
[ 2327.397031] ^
[ 2327.401792] ffff881be8779880: fc fc fc fc fb fb fb fb fb fb fb fb fc fc fc fc
[ 2327.409850] ffff881be8779900: 00 00 00 00 00 04 fc fc fc fc fc fc 00 00 00 00
[ 2327.417907] ==================================================================
This fixes CVE-2017-7558.
References: https://bugzilla.redhat.com/show_bug.cgi?id=1480266
Fixes: 8f840e47f190 ("sctp: add the sctp_diag.c file")
Cc: Xin Long <lucien.xin@xxxxxxxxx>
Cc: Vlad Yasevich <vyasevich@xxxxxxxxx>
Cc: Neil Horman <nhorman@xxxxxxxxxxxxx>
Signed-off-by: Stefano Brivio <sbrivio@xxxxxxxxxx>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>
Reviewed-by: Xin Long <lucien.xin@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/sctp/sctp_diag.c | 7 +++++--
net/sctp/socket.c | 3 +--
2 files changed, 6 insertions(+), 4 deletions(-)
--- a/net/sctp/sctp_diag.c
+++ b/net/sctp/sctp_diag.c
@@ -70,7 +70,8 @@ static int inet_diag_msg_sctpladdrs_fill
info = nla_data(attr);
list_for_each_entry_rcu(laddr, address_list, list) {
- memcpy(info, &laddr->a, addrlen);
+ memcpy(info, &laddr->a, sizeof(laddr->a));
+ memset(info + sizeof(laddr->a), 0, addrlen - sizeof(laddr->a));
info += addrlen;
}
@@ -93,7 +94,9 @@ static int inet_diag_msg_sctpaddrs_fill(
info = nla_data(attr);
list_for_each_entry(from, &asoc->peer.transport_addr_list,
transports) {
- memcpy(info, &from->ipaddr, addrlen);
+ memcpy(info, &from->ipaddr, sizeof(from->ipaddr));
+ memset(info + sizeof(from->ipaddr), 0,
+ addrlen - sizeof(from->ipaddr));
info += addrlen;
}
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4373,8 +4373,7 @@ int sctp_get_sctp_info(struct sock *sk,
info->sctpi_ictrlchunks = asoc->stats.ictrlchunks;
prim = asoc->peer.primary_path;
- memcpy(&info->sctpi_p_address, &prim->ipaddr,
- sizeof(struct sockaddr_storage));
+ memcpy(&info->sctpi_p_address, &prim->ipaddr, sizeof(prim->ipaddr));
info->sctpi_p_state = prim->state;
info->sctpi_p_cwnd = prim->cwnd;
info->sctpi_p_srtt = prim->srtt;
Patches currently in stable-queue which might be from sbrivio@xxxxxxxxxx are
queue-4.9/ipv6-accept-64k-1-packet-length-in-ip6_find_1stfragopt.patch
queue-4.9/sctp-avoid-out-of-bounds-reads-from-address-storage.patch
queue-4.9/cxgb4-fix-stack-out-of-bounds-read-due-to-wrong-size-to-t4_record_mbox.patch