| From bb2d090d14af8556eb689d6004068ac21ad58270 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Sat, 12 Mar 2022 15:29:58 -0800 |
| Subject: net/packet: fix slab-out-of-bounds access in packet_recvmsg() |
| |
| From: Eric Dumazet <edumazet@google.com> |
| |
| [ Upstream commit c700525fcc06b05adfea78039de02628af79e07a ] |
| |
| syzbot found that when an AF_PACKET socket is using PACKET_COPY_THRESH |
| and mmap operations, tpacket_rcv() is queueing skbs with |
| garbage in skb->cb[], triggering a too big copy [1] |
| |
| Presumably, users of af_packet using mmap() already gets correct |
| metadata from the mapped buffer, we can simply make sure |
| to clear 12 bytes that might be copied to user space later. |
| |
| BUG: KASAN: stack-out-of-bounds in memcpy include/linux/fortify-string.h:225 [inline] |
| BUG: KASAN: stack-out-of-bounds in packet_recvmsg+0x56c/0x1150 net/packet/af_packet.c:3489 |
| Write of size 165 at addr ffffc9000385fb78 by task syz-executor233/3631 |
| |
| CPU: 0 PID: 3631 Comm: syz-executor233 Not tainted 5.17.0-rc7-syzkaller-02396-g0b3660695e80 #0 |
| Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 |
| Call Trace: |
| <TASK> |
| __dump_stack lib/dump_stack.c:88 [inline] |
| dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 |
| print_address_description.constprop.0.cold+0xf/0x336 mm/kasan/report.c:255 |
| __kasan_report mm/kasan/report.c:442 [inline] |
| kasan_report.cold+0x83/0xdf mm/kasan/report.c:459 |
| check_region_inline mm/kasan/generic.c:183 [inline] |
| kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189 |
| memcpy+0x39/0x60 mm/kasan/shadow.c:66 |
| memcpy include/linux/fortify-string.h:225 [inline] |
| packet_recvmsg+0x56c/0x1150 net/packet/af_packet.c:3489 |
| sock_recvmsg_nosec net/socket.c:948 [inline] |
| sock_recvmsg net/socket.c:966 [inline] |
| sock_recvmsg net/socket.c:962 [inline] |
| ____sys_recvmsg+0x2c4/0x600 net/socket.c:2632 |
| ___sys_recvmsg+0x127/0x200 net/socket.c:2674 |
| __sys_recvmsg+0xe2/0x1a0 net/socket.c:2704 |
| do_syscall_x64 arch/x86/entry/common.c:50 [inline] |
| do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 |
| entry_SYSCALL_64_after_hwframe+0x44/0xae |
| RIP: 0033:0x7fdfd5954c29 |
| Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 41 15 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 |
| RSP: 002b:00007ffcf8e71e48 EFLAGS: 00000246 ORIG_RAX: 000000000000002f |
| RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fdfd5954c29 |
| RDX: 0000000000000000 RSI: 0000000020000500 RDI: 0000000000000005 |
| RBP: 0000000000000000 R08: 000000000000000d R09: 000000000000000d |
| R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffcf8e71e60 |
| R13: 00000000000f4240 R14: 000000000000c1ff R15: 00007ffcf8e71e54 |
| </TASK> |
| |
| addr ffffc9000385fb78 is located in stack of task syz-executor233/3631 at offset 32 in frame: |
| ____sys_recvmsg+0x0/0x600 include/linux/uio.h:246 |
| |
| this frame has 1 object: |
| [32, 160) 'addr' |
| |
| Memory state around the buggy address: |
| ffffc9000385fa80: 00 04 f3 f3 f3 f3 f3 00 00 00 00 00 00 00 00 00 |
| ffffc9000385fb00: 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 |
| >ffffc9000385fb80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f3 |
| ^ |
| ffffc9000385fc00: f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 f1 |
| ffffc9000385fc80: f1 f1 f1 00 f2 f2 f2 00 f2 f2 f2 00 00 00 00 00 |
| ================================================================== |
| |
| Fixes: 0fb375fb9b93 ("[AF_PACKET]: Allow for > 8 byte hardware addresses.") |
| Signed-off-by: Eric Dumazet <edumazet@google.com> |
| Reported-by: syzbot <syzkaller@googlegroups.com> |
| Link: https://lore.kernel.org/r/20220312232958.3535620-1-eric.dumazet@gmail.com |
| Signed-off-by: Jakub Kicinski <kuba@kernel.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| net/packet/af_packet.c | 11 ++++++++++- |
| 1 file changed, 10 insertions(+), 1 deletion(-) |
| |
| diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c |
| index bd7e8d406c71..d65051959f85 100644 |
| --- a/net/packet/af_packet.c |
| +++ b/net/packet/af_packet.c |
| @@ -2246,8 +2246,11 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, |
| copy_skb = skb_get(skb); |
| skb_head = skb->data; |
| } |
| - if (copy_skb) |
| + if (copy_skb) { |
| + memset(&PACKET_SKB_CB(copy_skb)->sa.ll, 0, |
| + sizeof(PACKET_SKB_CB(copy_skb)->sa.ll)); |
| skb_set_owner_r(copy_skb, sk); |
| + } |
| } |
| snaplen = po->rx_ring.frame_size - macoff; |
| if ((int)snaplen < 0) { |
| @@ -3406,6 +3409,8 @@ static int packet_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, |
| sock_recv_ts_and_drops(msg, sk, skb); |
| |
| if (msg->msg_name) { |
| + const size_t max_len = min(sizeof(skb->cb), |
| + sizeof(struct sockaddr_storage)); |
| int copy_len; |
| |
| /* If the address length field is there to be filled |
| @@ -3428,6 +3433,10 @@ static int packet_recvmsg(struct socket *sock, struct msghdr *msg, size_t len, |
| msg->msg_namelen = sizeof(struct sockaddr_ll); |
| } |
| } |
| + if (WARN_ON_ONCE(copy_len > max_len)) { |
| + copy_len = max_len; |
| + msg->msg_namelen = copy_len; |
| + } |
| memcpy(msg->msg_name, &PACKET_SKB_CB(skb)->sa, copy_len); |
| } |
| |
| -- |
| 2.34.1 |
| |