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Filename Latest commit message Latest commit date
Hillf Danton 86f4ac7ca4 tty: n_gsm: check error while registering tty devices
[ Upstream commit 0a360e8b65d62fe1a994f0a8da4f8d20877b2100 ]

Add the error path for registering tty devices and roll back in case of error
in bid to avoid the UAF like the below one reported.

Plus syzbot reported general protection fault in cdev_del() on Sep 24, 2020
and both cases are down to the kobject_put() in tty_cdev_add().

 ------------[ cut here ]------------
 refcount_t: underflow; use-after-free.
 WARNING: CPU: 1 PID: 8923 at lib/refcount.c:28
 refcount_warn_saturate+0x1cf/0x210 -origin/lib/refcount.c:28
 Modules linked in:
 CPU: 1 PID: 8923 Comm: executor Not tainted 5.12.0-rc5+ #8
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
 1.13.0-1ubuntu1.1 04/01/2014
 RIP: 0010:refcount_warn_saturate+0x1cf/0x210 -origin/lib/refcount.c:28
 Code: 4f ff ff ff e8 32 fa b5 fe 48 c7 c7 3d f8 f6 86 e8 d6 ab c6 fe
 c6 05 7c 34 67 04 01 48 c7 c7 68 f8 6d 86 31 c0 e8 81 2e 9d fe <0f> 0b
 e9 22 ff ff ff e8 05 fa b5 fe 48 c7 c7 3e f8 f6 86 e8 a9 ab
 RSP: 0018:ffffc90001633c60 EFLAGS: 00010246
 RAX: 15d08b2e34b77800 RBX: 0000000000000003 RCX: ffff88804c056c80
 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
 RBP: 0000000000000003 R08: ffffffff813767aa R09: 0001ffffffffffff
 R10: 0001ffffffffffff R11: ffff88804c056c80 R12: ffff888040b7d000
 R13: ffff88804c206938 R14: ffff88804c206900 R15: ffff888041b18488
 FS:  00000000022c9940(0000) GS:ffff88807ec00000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007f9f9b122008 CR3: 0000000044b4b000 CR4: 0000000000750ee0
 PKRU: 55555554
 Call Trace:
  __refcount_sub_and_test -origin/./include/linux/refcount.h:283 [inline]
  __refcount_dec_and_test -origin/./include/linux/refcount.h:315 [inline]
  refcount_dec_and_test -origin/./include/linux/refcount.h:333 [inline]
  kref_put -origin/./include/linux/kref.h:64 [inline]
  kobject_put+0x17b/0x180 -origin/lib/kobject.c:753
  cdev_del+0x4b/0x50 -origin/fs/char_dev.c:597
  tty_unregister_device+0x99/0xd0 -origin/drivers/tty/tty_io.c:3343
  gsmld_detach_gsm -origin/drivers/tty/n_gsm.c:2409 [inline]
  gsmld_close+0x6c/0x140 -origin/drivers/tty/n_gsm.c:2478
  tty_ldisc_close -origin/drivers/tty/tty_ldisc.c:488 [inline]
  tty_ldisc_kill -origin/drivers/tty/tty_ldisc.c:636 [inline]
  tty_ldisc_release+0x1b6/0x400 -origin/drivers/tty/tty_ldisc.c:809
  tty_release_struct+0x19/0xb0 -origin/drivers/tty/tty_io.c:1714
  tty_release+0x9ad/0xa00 -origin/drivers/tty/tty_io.c:1885
  __fput+0x260/0x4e0 -origin/fs/file_table.c:280
  ____fput+0x11/0x20 -origin/fs/file_table.c:313
  task_work_run+0x8e/0x110 -origin/kernel/task_work.c:140
  tracehook_notify_resume -origin/./include/linux/tracehook.h:189 [inline]
  exit_to_user_mode_loop -origin/kernel/entry/common.c:174 [inline]
  exit_to_user_mode_prepare+0x16b/0x1a0 -origin/kernel/entry/common.c:208
  __syscall_exit_to_user_mode_work -origin/kernel/entry/common.c:290 [inline]
  syscall_exit_to_user_mode+0x20/0x40 -origin/kernel/entry/common.c:301
  do_syscall_64+0x45/0x80 -origin/arch/x86/entry/common.c:56
  entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported-by: syzbot+c49fe6089f295a05e6f8@syzkaller.appspotmail.com
Reported-and-tested-by: Hao Sun <sunhao.th@gmail.com>
Signed-off-by: Hillf Danton <hdanton@sina.com>
Link: https://lore.kernel.org/r/20210412035758.1974-1-hdanton@sina.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-05-11 14:04:07 +02:00
arch x86/build: Propagate $(CLANG_FLAGS) to $(REALMODE_FLAGS) 2021-05-11 14:04:06 +02:00
block block: only update parent bi_status when bio fail 2021-04-16 11:46:38 +02:00
certs certs: Fix blacklist flag type confusion 2021-03-04 10:26:29 +01:00
crypto crypto: api - check for ERR pointers in crypto_destroy_tfm() 2021-05-11 14:04:05 +02:00
Documentation dt-bindings: net: ethernet-controller: fix typo in NVMEM 2021-04-14 08:24:18 +02:00
drivers tty: n_gsm: check error while registering tty devices 2021-05-11 14:04:07 +02:00
fs btrfs: fix metadata extent leak after failure to create subvolume 2021-05-11 14:04:04 +02:00
include usb: webcam: Invalid size of Processing Unit Descriptor 2021-05-11 14:04:05 +02:00
init init/Kconfig: make COMPILE_TEST depend on HAS_IOMEM 2021-04-10 13:34:32 +02:00
ipc
kernel genirq/matrix: Prevent allocation counter corruption 2021-05-11 14:04:05 +02:00
lib avoid __memcat_p link failure 2021-05-07 10:51:37 +02:00
LICENSES
mm mm: fix race by making init_zero_pfn() early_initcall 2021-04-07 14:47:42 +02:00
net gro: ensure frag0 meets IP header alignment 2021-04-21 12:56:17 +02:00
samples samples, bpf: Add missing munmap in xdpsock 2021-03-17 17:03:33 +01:00
scripts ftrace: Have recordmcount use w8 to read relp->r_info in arm64_is_fake_mcount 2021-03-09 11:09:39 +01:00
security integrity: double check iint_cache was initialized 2021-03-30 14:35:24 +02:00
sound ALSA: usb-audio: Add MIDI quirk for Vox ToneLab EX 2021-05-07 10:51:37 +02:00
tools perf ftrace: Fix access to pid in array when setting a pid filter 2021-05-07 10:51:37 +02:00
usr
virt KVM: arm64: Ensure I-cache isolation between vcpus of a same VM 2021-03-17 17:03:57 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile Linux 5.4.117 2021-05-07 10:51:38 +02:00
README

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.