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Oleksij Rempel 00d4e14d2e can: j1939: j1939_sk_bind(): take priv after lock is held
syzbot reproduced following crash:

===============================================================================
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 9844 Comm: syz-executor.0 Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:__lock_acquire+0x1254/0x4a00 kernel/locking/lockdep.c:3828
Code: 00 0f 85 96 24 00 00 48 81 c4 f0 00 00 00 5b 41 5c 41 5d 41 5e 41
5f 5d c3 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 <80> 3c 02
00 0f 85 0b 28 00 00 49 81 3e 20 19 78 8a 0f 84 5f ee ff
RSP: 0018:ffff888099c3fb48 EFLAGS: 00010006
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000218 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffff888099c3fc60 R08: 0000000000000001 R09: 0000000000000001
R10: fffffbfff146e1d0 R11: ffff888098720400 R12: 00000000000010c0
R13: 0000000000000000 R14: 00000000000010c0 R15: 0000000000000000
FS:  00007f0559e98700(0000) GS:ffff8880ae800000(0000)
knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe4d89e0000 CR3: 0000000099606000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4485
 __raw_spin_lock_bh include/linux/spinlock_api_smp.h:135 [inline]
 _raw_spin_lock_bh+0x33/0x50 kernel/locking/spinlock.c:175
 spin_lock_bh include/linux/spinlock.h:343 [inline]
 j1939_jsk_del+0x32/0x210 net/can/j1939/socket.c:89
 j1939_sk_bind+0x2ea/0x8f0 net/can/j1939/socket.c:448
 __sys_bind+0x239/0x290 net/socket.c:1648
 __do_sys_bind net/socket.c:1659 [inline]
 __se_sys_bind net/socket.c:1657 [inline]
 __x64_sys_bind+0x73/0xb0 net/socket.c:1657
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a679
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f0559e97c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000031
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a679
RDX: 0000000000000018 RSI: 0000000020000240 RDI: 0000000000000003
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0559e986d4
R13: 00000000004c09e9 R14: 00000000004d37d0 R15: 00000000ffffffff
Modules linked in:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 9844 at kernel/locking/mutex.c:1419
mutex_trylock+0x279/0x2f0 kernel/locking/mutex.c:1427
===============================================================================

This issues was caused by null pointer deference. Where j1939_sk_bind()
was using currently not existing priv.

Possible scenario may look as following:
cpu0                                    cpu1
bind()
                                        bind()
 j1939_sk_bind()
                                         j1939_sk_bind()
  priv = jsk->priv;
                                         priv = jsk->priv;
  lock_sock(sock->sk);
  priv = j1939_netdev_start(ndev);
  j1939_jsk_add(priv, jsk);
    jsk->priv = priv;
  relase_sock(sock->sk);
                                         lock_sock(sock->sk);
                                         j1939_jsk_del(priv, jsk);
                                         ..... ooops ......

With this patch we move "priv = jsk->priv;" after the lock, to avoid
assigning of wrong priv pointer.

Reported-by: syzbot+99e9e1b200a1e363237d@syzkaller.appspotmail.com
Fixes: 9d71dd0c70 ("can: add support of SAE J1939 protocol")
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Cc: linux-stable <stable@vger.kernel.org> # >= v5.4
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
2019-12-08 11:52:02 +01:00
arch Merge branch 'akpm' (patches from Andrew) 2019-12-01 20:36:41 -08:00
block compat_ioctl: remove most of fs/compat_ioctl.c 2019-12-01 13:46:15 -08:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2019-11-25 19:49:58 -08:00
Documentation Merge branch 'akpm' (patches from Andrew) 2019-12-01 20:36:41 -08:00
drivers r8169: fix rtl_hw_jumbo_disable for RTL8168evl 2019-12-07 14:23:06 -08:00
fs Merge branch 'akpm' (patches from Andrew) 2019-12-01 20:36:41 -08:00
include inet: protect against too small mtu values. 2019-12-07 11:55:11 -08:00
init Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2019-12-01 13:26:18 -08:00
ipc y2038: remove CONFIG_64BIT_TIME 2019-11-15 14:38:27 +01:00
kernel bpf: Fix a bug when getting subprog 0 jited image in check_attach_btf_id 2019-12-04 21:20:07 -08:00
lib Merge branch 'akpm' (patches from Andrew) 2019-12-01 20:36:41 -08:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm/page_io.c: annotate refault stalls from swap_readpage 2019-12-01 12:59:11 -08:00
net can: j1939: j1939_sk_bind(): take priv after lock is held 2019-12-08 11:52:02 +01:00
samples samples/bpf: Fix broken xdp_rxq_info due to map order assumptions 2019-12-04 17:54:15 -08:00
scripts Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2019-12-02 10:50:29 -08:00
security y2038: syscall implementation cleanups 2019-12-01 14:00:59 -08:00
sound compat_ioctl: remove most of fs/compat_ioctl.c 2019-12-01 13:46:15 -08:00
tools net/tls: Fix return values to avoid ENOTSUPP 2019-12-06 20:15:39 -08:00
usr kbuild: update compile-test header list for v5.4-rc2 2019-10-05 15:29:49 +09:00
virt KVM: Fix jump label out_free_* in kvm_init() 2019-11-23 11:29:17 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap Merge branch 'efi-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-11-26 14:52:11 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS MAINTAINERS: Add myself as a maintainer for TCAN4x5x 2019-12-08 11:52:01 +01:00
Makefile Linux 5.4 2019-11-24 16:32:01 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

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.