[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <CAKx+4-pUdYEKivbsm6WyxDyQ0W4fAiOxRFmBqPxVXhwvicaaYA@mail.gmail.com>
Date: Thu, 19 Jan 2023 01:56:46 +0530
From: Rohit Keshri <rkeshri@...hat.com>
To: oss-security@...ts.openwall.com
Subject: Re: null pointer dereference in Linux kernel
Hello Team,
CVE-2023-0394 assigned.
On Wed, Jan 18, 2023 at 2:02 PM Kyle Zeng <zengyhkyle@...il.com> wrote:
> Hi there,
>
> I recently found a null pointer dereference in Linux kernel that
> affects multiple kernel versions. According to the versions that got
> patched, the vulnerability affects 6.1, 5.15, 5.10, 5.4, and 4.19.
>
> [Root Cause Analysis]
> The bug is in "rawv6_push_pending_frames" function in net/ipv6/raw.c.
> According to Herbert Xu, who fixed the bug, the root cause is that
> "total_len = inet_sk(sk)->cork.base.length" in this function also
> counts the length of the extension header (+ the amount of valid data
> in the socket cork queue). In the vulnerable version of the function,
> it directly uses the length as the amount of data in the cork queue.
> In the following code:
>
> struct sk_buff *csum_skb = NULL;
> ...
> skb_queue_walk(&sk->sk_write_queue, skb) {
> ...
> if (offset >= len) {
> offset -= len;
> continue;
> }
> csum_skb = skb;
> }
> skb = csum_skb;
>
> If the `offset` is larger than the amount of data in the socket cork
> queue but smaller than valid data length + extension header length,
> then the loop shown above will always enter the "if (offset >= len)"
> branch. As a result, csum_skb will never be set. Consequently, the
> final skb variable will be set to NULL.
>
> Null dereference happens in the following "skb_transport_offset(skb);"
> call.
>
> [Patch]
> I have contacted Linux kernel team and helped them prepare a patch.
> The patch to this bug has been merged into the mainline and stable
> trees:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=cb3e9864cdbe35ff6378966660edbcbac955fe17
>
> This bug does not have a CVE number assigned yet. I'll appreciate it
> if someone from the list can give it a CVE number to notify other
> vendors about its security implication.
>
> A crash report is attached to the email. And a poc that triggers oops
> can be found here:
> https://lore.kernel.org/netdev/Y7s%2FFofVXLwoVgWt@westworld/
>
> Best,
> Kyle Zeng
>
>
> =====================================
> general protection fault, probably for non-canonical address
> 0xdffffc0000000018: 0000 [#1] SMP KASAN PTI
> KASAN: null-ptr-deref in range [0x00000000000000c0-0x00000000000000c7]
> CPU: 0 PID: 619 Comm: syz-executor390 Not tainted 5.10.140+ #1
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1
> 04/01/2014
> RIP: 0010:skb_transport_header include/linux/skbuff.h:2500 [inline]
> RIP: 0010:skb_transport_offset include/linux/skbuff.h:2606 [inline]
> RIP: 0010:rawv6_push_pending_frames net/ipv6/raw.c:593 [inline]
> RIP: 0010:rawv6_sendmsg+0x4368/0x5db0 net/ipv6/raw.c:956
> Code: e8 cd ca e0 fb e9 51 fe ff ff e8 c3 7b 61 fb 49 89 dd 48 bd 00
> 00 00 00 00 fc ff df 49 8d bd c0 00 00 00 48 89 f8 48 c1 e8 03 <80> 3c
> 28 00 74 05 e8 bd ca e0 fb 49 8b 9d c0 00 00 00 49 8d bd b2
> RSP: 0018:ffff888013ddf7e8 EFLAGS: 00010206
> RAX: 0000000000000018 RBX: 0000000000000000 RCX: ffff888011f05500
> RDX: 0000000000000000 RSI: 0000000000000004 RDI: 00000000000000c0
> RBP: dffffc0000000000 R08: dffffc0000000000 R09: ffffed10027a9afc
> R10: 0000000000000000 R11: 0000000000000000 R12: 00000000479c45b8
> R13: 0000000000000000 R14: ffff888013d4d800 R15: 00000000000000d8
> FS: 00005555560ca3c0(0000) GS:ffff88806b800000(0000)
> knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000020001000 CR3: 000000000eb5a002 CR4: 0000000000170ef0
> Call Trace:
> sock_sendmsg_nosec net/socket.c:651 [inline]
> sock_sendmsg net/socket.c:671 [inline]
> kernel_sendmsg+0x20a/0x230 net/socket.c:691
> sock_no_sendpage+0xde/0x130 net/core/sock.c:2852
> kernel_sendpage+0x4c8/0x530 net/socket.c:3514
> sock_sendpage+0x83/0xb0 net/socket.c:944
> pipe_to_sendpage+0x4c0/0x630 fs/splice.c:364
> splice_from_pipe_feed fs/splice.c:418 [inline]
> __splice_from_pipe+0x655/0xf60 fs/splice.c:562
> splice_from_pipe fs/splice.c:597 [inline]
> generic_splice_sendpage+0x132/0x1a0 fs/splice.c:743
> do_splice_from fs/splice.c:764 [inline]
> do_splice+0x1ea8/0x2da0 fs/splice.c:1057
> __do_splice fs/splice.c:1135 [inline]
> __do_sys_splice fs/splice.c:1341 [inline]
> __se_sys_splice+0x935/0xdc0 fs/splice.c:1323
> do_syscall_64+0x13a/0x160 arch/x86/entry/common.c:46
> entry_SYSCALL_64_after_hwframe+0x61/0xc6
> RIP: 0033:0x7f111d8c47dd
> Code: c3 e8 e7 22 00 00 0f 1f 80 00 00 00 00 f3 0f 1e fa 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 b8 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fff0105cb48 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f111d8c47dd
> RDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000003
> RBP: 00007fff0105cb80 R08: 000000000804ffe2 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 000000000000bbd1 R14: 00007fff0105cb64 R15: 00007fff0105cb70
> Modules linked in:
> ---[ end trace 66de936c85813c54 ]---
> RIP: 0010:skb_transport_header include/linux/skbuff.h:2500 [inline]
> RIP: 0010:skb_transport_offset include/linux/skbuff.h:2606 [inline]
> RIP: 0010:rawv6_push_pending_frames net/ipv6/raw.c:593 [inline]
> RIP: 0010:rawv6_sendmsg+0x4368/0x5db0 net/ipv6/raw.c:956
> Code: e8 cd ca e0 fb e9 51 fe ff ff e8 c3 7b 61 fb 49 89 dd 48 bd 00
> 00 00 00 00 fc ff df 49 8d bd c0 00 00 00 48 89 f8 48 c1 e8 03 <80> 3c
> 28 00 74 05 e8 bd ca e0 fb 49 8b 9d c0 00 00 00 49 8d bd b2
> RSP: 0018:ffff888013ddf7e8 EFLAGS: 00010206
> RAX: 0000000000000018 RBX: 0000000000000000 RCX: ffff888011f05500
> RDX: 0000000000000000 RSI: 0000000000000004 RDI: 00000000000000c0
> RBP: dffffc0000000000 R08: dffffc0000000000 R09: ffffed10027a9afc
> R10: 0000000000000000 R11: 0000000000000000 R12: 00000000479c45b8
> R13: 0000000000000000 R14: ffff888013d4d800 R15: 00000000000000d8
> FS: 00005555560ca3c0(0000) GS:ffff88806b800000(0000)
> knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000020001000 CR3: 000000000eb5a002 CR4: 0000000000170ef0
> ----------------
> Code disassembly (best guess):
> 0: e8 cd ca e0 fb call 0xfbe0cad2
> 5: e9 51 fe ff ff jmp 0xfffffe5b
> a: e8 c3 7b 61 fb call 0xfb617bd2
> f: 49 89 dd mov %rbx,%r13
> 12: 48 bd 00 00 00 00 00 movabs $0xdffffc0000000000,%rbp
> 19: fc ff df
> 1c: 49 8d bd c0 00 00 00 lea 0xc0(%r13),%rdi
> 23: 48 89 f8 mov %rdi,%rax
> 26: 48 c1 e8 03 shr $0x3,%rax
> * 2a: 80 3c 28 00 cmpb $0x0,(%rax,%rbp,1) <-- trapping
> instruction
> 2e: 74 05 je 0x35
> 30: e8 bd ca e0 fb call 0xfbe0caf2
> 35: 49 8b 9d c0 00 00 00 mov 0xc0(%r13),%rbx
> 3c: 49 rex.WB
> 3d: 8d .byte 0x8d
> 3e: bd .byte 0xbd
> 3f: b2 .byte 0xb2
>
>
Powered by blists - more mailing lists
Please check out the
Open Source Software Security Wiki, which is counterpart to this
mailing list.
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
