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2dda640040
syzkaller was able to trigger a divide by 0 in TCP stack [1]
Issue here is that keepalive timer needs to be updated to not attempt
to send a probe if the connection setup was deferred using
TCP_FASTOPEN_CONNECT socket option added in linux-4.11
[1]
divide error: 0000 [#1] SMP
CPU: 18 PID: 0 Comm: swapper/18 Not tainted
task: ffff986f62f4b040 ti: ffff986f62fa2000 task.ti: ffff986f62fa2000
RIP: 0010:[<ffffffff8409cc0d>] [<ffffffff8409cc0d>] __tcp_select_window+0x8d/0x160
Call Trace:
<IRQ>
[<ffffffff8409d951>] tcp_transmit_skb+0x11/0x20
[<ffffffff8409da21>] tcp_xmit_probe_skb+0xc1/0xe0
[<ffffffff840a0ee8>] tcp_write_wakeup+0x68/0x160
[<ffffffff840a151b>] tcp_keepalive_timer+0x17b/0x230
[<ffffffff83b3f799>] call_timer_fn+0x39/0xf0
[<ffffffff83b40797>] run_timer_softirq+0x1d7/0x280
[<ffffffff83a04ddb>] __do_softirq+0xcb/0x257
[<ffffffff83ae03ac>] irq_exit+0x9c/0xb0
[<ffffffff83a04c1a>] smp_apic_timer_interrupt+0x6a/0x80
[<ffffffff83a03eaf>] apic_timer_interrupt+0x7f/0x90
<EOI>
[<ffffffff83fed2ea>] ? cpuidle_enter_state+0x13a/0x3b0
[<ffffffff83fed2cd>] ? cpuidle_enter_state+0x11d/0x3b0
Tested:
Following packetdrill no longer crashes the kernel
`echo 0 >/proc/sys/net/ipv4/tcp_timestamps`
// Cache warmup: send a Fast Open cookie request
0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+0 fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0
+0 setsockopt(3, SOL_TCP, TCP_FASTOPEN_CONNECT, [1], 4) = 0
+0 connect(3, ..., ...) = -1 EINPROGRESS (Operation is now in progress)
+0 > S 0:0(0) <mss 1460,nop,nop,sackOK,nop,wscale 8,FO,nop,nop>
+.01 < S. 123:123(0) ack 1 win 14600 <mss 1460,nop,nop,sackOK,nop,wscale 6,FO abcd1234,nop,nop>
+0 > . 1:1(0) ack 1
+0 close(3) = 0
+0 > F. 1:1(0) ack 1
+0 < F. 1:1(0) ack 2 win 92
+0 > . 2:2(0) ack 2
+0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 4
+0 fcntl(4, F_SETFL, O_RDWR|O_NONBLOCK) = 0
+0 setsockopt(4, SOL_TCP, TCP_FASTOPEN_CONNECT, [1], 4) = 0
+0 setsockopt(4, SOL_SOCKET, SO_KEEPALIVE, [1], 4) = 0
+.01 connect(4, ..., ...) = 0
+0 setsockopt(4, SOL_TCP, TCP_KEEPIDLE, [5], 4) = 0
+10 close(4) = 0
`echo 1 >/proc/sys/net/ipv4/tcp_timestamps`
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.