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Eric Dumazet 50895b9de1 tcp: highest_sack fix
syzbot easily found a regression added in our latest patches [1]

No longer set tp->highest_sack to the head of the send queue since
this is not logical and error prone.

Only sack processing should maintain the pointer to an skb from rtx queue.

We might in the future only remember the sequence instead of a pointer to skb,
since rb-tree should allow a fast lookup.

[1]
BUG: KASAN: use-after-free in tcp_highest_sack_seq include/net/tcp.h:1706 [inline]
BUG: KASAN: use-after-free in tcp_ack+0x42bb/0x4fd0 net/ipv4/tcp_input.c:3537
Read of size 4 at addr ffff8801c154faa8 by task syz-executor4/12860

CPU: 0 PID: 12860 Comm: syz-executor4 Not tainted 4.14.0-next-20171113+ #41
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x25b/0x340 mm/kasan/report.c:409
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429
 tcp_highest_sack_seq include/net/tcp.h:1706 [inline]
 tcp_ack+0x42bb/0x4fd0 net/ipv4/tcp_input.c:3537
 tcp_rcv_established+0x672/0x18a0 net/ipv4/tcp_input.c:5439
 tcp_v4_do_rcv+0x2ab/0x7d0 net/ipv4/tcp_ipv4.c:1468
 sk_backlog_rcv include/net/sock.h:909 [inline]
 __release_sock+0x124/0x360 net/core/sock.c:2264
 release_sock+0xa4/0x2a0 net/core/sock.c:2778
 tcp_sendmsg+0x3a/0x50 net/ipv4/tcp.c:1462
 inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:763
 sock_sendmsg_nosec net/socket.c:632 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:642
 ___sys_sendmsg+0x75b/0x8a0 net/socket.c:2048
 __sys_sendmsg+0xe5/0x210 net/socket.c:2082
 SYSC_sendmsg net/socket.c:2093 [inline]
 SyS_sendmsg+0x2d/0x50 net/socket.c:2089
 entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452879
RSP: 002b:00007fc9761bfbe8 EFLAGS: 00000212 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000758020 RCX: 0000000000452879
RDX: 0000000000000000 RSI: 0000000020917fc8 RDI: 0000000000000015
RBP: 0000000000000086 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006ee3a0
R13: 00000000ffffffff R14: 00007fc9761c06d4 R15: 0000000000000000

Allocated by task 12860:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc_node+0x144/0x760 mm/slab.c:3638
 __alloc_skb+0xf1/0x780 net/core/skbuff.c:193
 alloc_skb_fclone include/linux/skbuff.h:1023 [inline]
 sk_stream_alloc_skb+0x11d/0x900 net/ipv4/tcp.c:870
 tcp_sendmsg_locked+0x1341/0x3b80 net/ipv4/tcp.c:1299
 tcp_sendmsg+0x2f/0x50 net/ipv4/tcp.c:1461
 inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:763
 sock_sendmsg_nosec net/socket.c:632 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:642
 SYSC_sendto+0x358/0x5a0 net/socket.c:1749
 SyS_sendto+0x40/0x50 net/socket.c:1717
 entry_SYSCALL_64_fastpath+0x1f/0x96

Freed by task 12860:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3492 [inline]
 kmem_cache_free+0x77/0x280 mm/slab.c:3750
 kfree_skbmem+0xdd/0x1d0 net/core/skbuff.c:603
 __kfree_skb+0x1d/0x20 net/core/skbuff.c:642
 sk_wmem_free_skb include/net/sock.h:1419 [inline]
 tcp_rtx_queue_unlink_and_free include/net/tcp.h:1682 [inline]
 tcp_clean_rtx_queue net/ipv4/tcp_input.c:3111 [inline]
 tcp_ack+0x1b17/0x4fd0 net/ipv4/tcp_input.c:3593
 tcp_rcv_established+0x672/0x18a0 net/ipv4/tcp_input.c:5439
 tcp_v4_do_rcv+0x2ab/0x7d0 net/ipv4/tcp_ipv4.c:1468
 sk_backlog_rcv include/net/sock.h:909 [inline]
 __release_sock+0x124/0x360 net/core/sock.c:2264
 release_sock+0xa4/0x2a0 net/core/sock.c:2778
 tcp_sendmsg+0x3a/0x50 net/ipv4/tcp.c:1462
 inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:763
 sock_sendmsg_nosec net/socket.c:632 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:642
 ___sys_sendmsg+0x75b/0x8a0 net/socket.c:2048
 __sys_sendmsg+0xe5/0x210 net/socket.c:2082
 SYSC_sendmsg net/socket.c:2093 [inline]
 SyS_sendmsg+0x2d/0x50 net/socket.c:2089
 entry_SYSCALL_64_fastpath+0x1f/0x96

The buggy address belongs to the object at ffff8801c154fa80
 which belongs to the cache skbuff_fclone_cache of size 456
The buggy address is located 40 bytes inside of
 456-byte region [ffff8801c154fa80, ffff8801c154fc48)
The buggy address belongs to the page:
page:ffffea00070553c0 count:1 mapcount:0 mapping:ffff8801c154f080 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801c154f080 0000000000000000 0000000100000006
raw: ffffea00070a5a20 ffffea0006a18360 ffff8801d9ca0500 0000000000000000
page dumped because: kasan: bad access detected

Fixes: 737ff31456 ("tcp: use sequence distance to detect reordering")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-11-15 19:48:42 +09:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-12 09:17:05 +09:00
block License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-11-06 09:05:03 -08:00
Documentation net: Mention net-next status web page in netdev-FAQ.txt 2017-11-14 21:11:57 +09:00
drivers geneve: fix fill_info when link down 2017-11-15 19:47:11 +09:00
firmware License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-04 09:26:51 +09:00
include tcp: highest_sack fix 2017-11-15 19:48:42 +09:00
init License cleanup: add SPDX license identifiers to some files 2017-11-02 10:04:46 -07:00
ipc License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kernel bpf: fix lockdep splat 2017-11-15 19:46:32 +09:00
lib net: netlink: Update attr validation to require exact length for some types 2017-11-11 15:14:38 +09:00
mm mm, swap: fix race between swap count continuation operations 2017-11-03 07:39:19 -07:00
net tcp: highest_sack fix 2017-11-15 19:48:42 +09:00
samples xdp: sample: Missing curly braces in read_route() 2017-11-14 22:00:13 +09:00
scripts Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-10 10:00:18 +09:00
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sound sound fixes for 4.14 2017-11-09 09:58:11 -08:00
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usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt Fixes for interrupt controller emulation in ARM/ARM64 and x86, plus a one-liner 2017-11-04 11:44:55 -07:00
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COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
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MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-11-12 09:17:05 +09:00
Makefile Linux 4.14-rc8 2017-11-05 13:05:14 -08:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

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.