queue-4.4/fs-proc-proc_sysctl.c-fix-a-null-pointer-dereference.patch

   1 From 89189557b47b35683a27c80ee78aef18248eefb4 Mon Sep 17 00:00:00 2001
   2 From: YueHaibing <yuehaibing@huawei.com>
   3 Date: Thu, 25 Apr 2019 22:24:05 -0700
   4 Subject: fs/proc/proc_sysctl.c: Fix a NULL pointer dereference
   5
   6 From: YueHaibing <yuehaibing@huawei.com>
   7
   8 commit 89189557b47b35683a27c80ee78aef18248eefb4 upstream.
   9
  10 Syzkaller report this:
  11
  12   sysctl could not get directory: /net//bridge -12
  13   kasan: CONFIG_KASAN_INLINE enabled
  14   kasan: GPF could be caused by NULL-ptr deref or user memory access
  15   general protection fault: 0000 [#1] SMP KASAN PTI
  16   CPU: 1 PID: 7027 Comm: syz-executor.0 Tainted: G         C        5.1.0-rc3+ #8
  17   Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
  18   RIP: 0010:__write_once_size include/linux/compiler.h:220 [inline]
  19   RIP: 0010:__rb_change_child include/linux/rbtree_augmented.h:144 [inline]
  20   RIP: 0010:__rb_erase_augmented include/linux/rbtree_augmented.h:186 [inline]
  21   RIP: 0010:rb_erase+0x5f4/0x19f0 lib/rbtree.c:459
  22   Code: 00 0f 85 60 13 00 00 48 89 1a 48 83 c4 18 5b 5d 41 5c 41 5d 41 5e 41 5f c3 48 89 f2 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 75 0c 00 00 4d 85 ed 4c 89 2e 74 ce 4c 89 ea 48
  23   RSP: 0018:ffff8881bb507778 EFLAGS: 00010206
  24   RAX: dffffc0000000000 RBX: ffff8881f224b5b8 RCX: ffffffff818f3f6a
  25   RDX: 000000000000000a RSI: 0000000000000050 RDI: ffff8881f224b568
  26   RBP: 0000000000000000 R08: ffffed10376a0ef4 R09: ffffed10376a0ef4
  27   R10: 0000000000000001 R11: ffffed10376a0ef4 R12: ffff8881f224b558
  28   R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
  29   FS:  00007f3e7ce13700(0000) GS:ffff8881f7300000(0000) knlGS:0000000000000000
  30   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  31   CR2: 00007fd60fbe9398 CR3: 00000001cb55c001 CR4: 00000000007606e0
  32   DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  33   DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  34   PKRU: 55555554
  35   Call Trace:
  36    erase_entry fs/proc/proc_sysctl.c:178 [inline]
  37    erase_header+0xe3/0x160 fs/proc/proc_sysctl.c:207
  38    start_unregistering fs/proc/proc_sysctl.c:331 [inline]
  39    drop_sysctl_table+0x558/0x880 fs/proc/proc_sysctl.c:1631
  40    get_subdir fs/proc/proc_sysctl.c:1022 [inline]
  41    __register_sysctl_table+0xd65/0x1090 fs/proc/proc_sysctl.c:1335
  42    br_netfilter_init+0x68/0x1000 [br_netfilter]
  43    do_one_initcall+0xbc/0x47d init/main.c:901
  44    do_init_module+0x1b5/0x547 kernel/module.c:3456
  45    load_module+0x6405/0x8c10 kernel/module.c:3804
  46    __do_sys_finit_module+0x162/0x190 kernel/module.c:3898
  47    do_syscall_64+0x9f/0x450 arch/x86/entry/common.c:290
  48    entry_SYSCALL_64_after_hwframe+0x49/0xbe
  49   Modules linked in: br_netfilter(+) backlight comedi(C) hid_sensor_hub max3100 ti_ads8688 udc_core fddi snd_mona leds_gpio rc_streamzap mtd pata_netcell nf_log_common rc_winfast udp_tunnel snd_usbmidi_lib snd_usb_toneport snd_usb_line6 snd_rawmidi snd_seq_device snd_hwdep videobuf2_v4l2 videobuf2_common videodev media videobuf2_vmalloc videobuf2_memops rc_gadmei_rm008z 8250_of smm665 hid_tmff hid_saitek hwmon_vid rc_ati_tv_wonder_hd_600 rc_core pata_pdc202xx_old dn_rtmsg as3722 ad714x_i2c ad714x snd_soc_cs4265 hid_kensington panel_ilitek_ili9322 drm drm_panel_orientation_quirks ipack cdc_phonet usbcore phonet hid_jabra hid extcon_arizona can_dev industrialio_triggered_buffer kfifo_buf industrialio adm1031 i2c_mux_ltc4306 i2c_mux ipmi_msghandler mlxsw_core snd_soc_cs35l34 snd_soc_core snd_pcm_dmaengine snd_pcm snd_timer ac97_bus snd_compress snd soundcore gpio_da9055 uio ecdh_generic mdio_thunder of_mdio fixed_phy libphy mdio_cavium iptable_security iptable_raw iptable_mangle
  50    iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 iptable_filter bpfilter ip6_vti ip_vti ip_gre ipip sit tunnel4 ip_tunnel hsr veth netdevsim vxcan batman_adv cfg80211 rfkill chnl_net caif nlmon dummy team bonding vcan bridge stp llc ip6_gre gre ip6_tunnel tunnel6 tun joydev mousedev ppdev tpm kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel aesni_intel ide_pci_generic piix aes_x86_64 crypto_simd cryptd ide_core glue_helper input_leds psmouse intel_agp intel_gtt serio_raw ata_generic i2c_piix4 agpgart pata_acpi parport_pc parport floppy rtc_cmos sch_fq_codel ip_tables x_tables sha1_ssse3 sha1_generic ipv6 [last unloaded: br_netfilter]
  51   Dumping ftrace buffer:
  52      (ftrace buffer empty)
  53   ---[ end trace 68741688d5fbfe85 ]---
  54
  55 commit 23da9588037e ("fs/proc/proc_sysctl.c: fix NULL pointer
  56 dereference in put_links") forgot to handle start_unregistering() case,
  57 while header->parent is NULL, it calls erase_header() and as seen in the
  58 above syzkaller call trace, accessing &header->parent->root will trigger
  59 a NULL pointer dereference.
  60
  61 As that commit explained, there is also no need to call
  62 start_unregistering() if header->parent is NULL.
  63
  64 Link: http://lkml.kernel.org/r/20190409153622.28112-1-yuehaibing@huawei.com
  65 Fixes: 23da9588037e ("fs/proc/proc_sysctl.c: fix NULL pointer dereference in put_links")
  66 Fixes: 0e47c99d7fe25 ("sysctl: Replace root_list with links between sysctl_table_sets")
  67 Signed-off-by: YueHaibing <yuehaibing@huawei.com>
  68 Reported-by: Hulk Robot <hulkci@huawei.com>
  69 Reviewed-by: Kees Cook <keescook@chromium.org>
  70 Cc: Luis Chamberlain <mcgrof@kernel.org>
  71 Cc: Alexey Dobriyan <adobriyan@gmail.com>
  72 Cc: Al Viro <viro@zeniv.linux.org.uk>
  73 Cc: "Eric W. Biederman" <ebiederm@xmission.com>
  74 Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
  75 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
  76 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  77
  78 ---
  79  fs/proc/proc_sysctl.c |    6 ++++--
  80  1 file changed, 4 insertions(+), 2 deletions(-)
  81
  82 --- a/fs/proc/proc_sysctl.c
  83 +++ b/fs/proc/proc_sysctl.c
  84 @@ -1550,9 +1550,11 @@ static void drop_sysctl_table(struct ctl
  85         if (--header->nreg)
  86                 return;
  87
  88 -       if (parent)
  89 +       if (parent) {
  90                 put_links(header);
  91 -       start_unregistering(header);
  92 +               start_unregistering(header);
  93 +       }
  94 +
  95         if (!--header->count)
  96                 kfree_rcu(header, rcu);
  97