[Zesty][PATCH 0/2] UBUNTU: SAUCE: net sched actions: access to uninitialized data and error handling

Colin Ian King colin.king at canonical.com
Thu Apr 13 13:16:46 UTC 2017


On 13/04/17 09:57, Fabian Gr├╝nbichler wrote:
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1682368
> 
> CC: Wolfang Bumiller <w.bumiller at proxmox.com>
> 
> == SRU Justification ==
> 
> Impact: adding a tc filter sometimes fails, potentially followed by kernel hangs and kernel NULL pointer dereference
> 
> Fix: proposed upstream by Wolfgang Bumiller [1,2]
> 
> Regression Potential: Since nobody else noticed this issue in 4.11 >= rc1 or Ubuntu 4.10 >= 15.17, and the fix only touches the broken code, the regression potential should be minimal ;)
> 
> 1: http://marc.info/?l=linux-netdev&m=149200746116365
> 2: http://marc.info/?l=linux-netdev&m=149200742616349
> 
> Commit 1045ba77a which was backported for #1674087 in
> fc0cef7a8ec1e63ee3405f642983dd86e04ab6cc (first released with
> Ubuntu-4.10.0-15.17) introduces the problematic code. Note that while the
> traces below were generated using a custom patched kernel, the same issue is
> reproducible using Ubuntu Zesty's 4.10.0-15.17 (and later) kernels.
> 
> The full cover letter of the proposed fix by my colleague Wolfgang Bumiller follows:
> 
> Commit 1045ba77a ("net sched actions: Add support for user cookies")
> added code to net/sched/act_api.c's tcf_action_init_1 using the `tb`
> nlattr array unconditionally, while it was otherwise used as well as
> initialized only when `name == NULL`:
> 
>  if (name == NULL) {
>   err = nla_parse_nested(tb, TCA_ACT_MAX, nla, NULL);
> 
> In the other case `nla` is instead passed over to ->init to be parsed
> there (using a different set of TCA_ enum values, iow. TCA_ACT_COOKIE
> then "clashes" with some other value). This lead to the following three
> example commands resulting in errors (sometimes followed by more traces
> and hangups some time later (although the hangups happened seconds or
> sometimes minutes later, sometimes not at all - results differed between
> different kernel versions (linux git-master vs ubuntu's mainline 4.11
> rc6 vs. pve 4.10.5 (based off ubuntu's zesty kernel where the commit is
> cherry-picked)...))):
> 
>  # ip link add ve0 type veth peer name ve0b
>  # tc qdisc add dev ve0 handle ffff: ingress
>  # tc filter add dev ve0 parent ffff: prio 50 basic police rate 1000bps burst 1000b drop
> 
> The 3rd command would sometimes succeed, sometimes error with:
> 
>  RTNETLINK answers: Invalid argument
>  We have an error talking to the kernel
> 
> and sometimes error with:
> 
>  RTNETLINK answers: Cannot allocate memory
>  We have an error talking to the kernel
> 
> In the latter case I assume `cklen` became negative, which passes the
> TC_COOKIE_MAX_SIZE check since it is signed but becomes unsigned later
> in kmemdup() (see the crash dump below)
> 
> When the `tc filter add` command fails a backtrace shows up in dmesg,
> added below.
> 
> I'm not sure why the TC_ACT_COOKIE code was added to tcf_action_init_1
> where it is now. It makes me think that it's supposed to be available
> universally, but the `name == NULL` check for how nla is used or passed
> to ->init() shows that the there are various different TC_ACT_* enums in
> use at this point, hence the 'RFC' part of the patches, I'm not that
> familiar with the code yet.
> 
> Backtrace when running `tc filter add`:
> 
>     Apr 12 11:31:38 testmachine kernel: ------------[ cut here ]------------
>     Apr 12 11:31:38 testmachine kernel: WARNING: CPU: 7 PID: 16596 at mm/page_alloc.c:3541 __alloc_pages_slowpath+0x9fe/0xba0
>     Apr 12 11:31:38 testmachine kernel: Modules linked in: act_police cls_basic sch_ingress veth nfsv3 nfs_acl nfs lockd grace ip6t_REJECT nf_reject_ipv6 nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables xt_mac ipt_REJECT nf_reject_ipv4 xt_physdev xt_comment nf_conntrack_ipv4 nf_defrag_ipv4 xt_tcpudp xt_mark xt_set xt_addrtype xt_multiport xt_conntrack nf_conntrack ip_set_hash_net ip_set arc4 md4 nls_utf8 cifs ccm fscache ipta
>     Apr 12 11:31:38 testmachine kernel: snd_hda_codec_realtek snd_hda_codec_generic aesni_intel aes_x86_64 crypto_simd drm_kms_helper glue_helper cryptd drm snd_hda_intel intel_cstate snd_hda_codec i2c_algo_bit fb_sys_fops snd_hda_core joydev syscopyarea snd_hwdep sysfillrect input_leds sysimgblt intel_rapl_perf snd_pcm snd_timer snd pcspkr soundcore mei_me lpc_ich mei shpchp tpm_infineon mac_hid wmi acpi_pad video vhost_net vhost macv
>     Apr 12 11:31:38 testmachine kernel: CPU: 7 PID: 16596 Comm: tc Tainted: P O 4.10.5-1-pve #1
>     Apr 12 11:31:38 testmachine kernel: Hardware name: ASUS All Series/Z97-A, BIOS 2801 11/11/2015
>     Apr 12 11:31:38 testmachine kernel: Call Trace:
>     Apr 12 11:31:38 testmachine kernel: dump_stack+0x63/0x81
>     Apr 12 11:31:38 testmachine kernel: __warn+0xcb/0xf0
>     Apr 12 11:31:38 testmachine kernel: warn_slowpath_null+0x1d/0x20
>     Apr 12 11:31:38 testmachine kernel: __alloc_pages_slowpath+0x9fe/0xba0
>     Apr 12 11:31:38 testmachine kernel: ? get_page_from_freelist+0x46a/0xb20
>     Apr 12 11:31:38 testmachine kernel: ? schedule+0x36/0x80
>     Apr 12 11:31:38 testmachine kernel: ? schedule_timeout+0x22a/0x3f0
>     Apr 12 11:31:38 testmachine kernel: __alloc_pages_nodemask+0x209/0x260
>     Apr 12 11:31:38 testmachine kernel: alloc_pages_current+0x95/0x140
>     Apr 12 11:31:38 testmachine kernel: kmalloc_order+0x18/0x40
>     Apr 12 11:31:38 testmachine kernel: kmalloc_order_trace+0x24/0xa0
>     Apr 12 11:31:38 testmachine kernel: __kmalloc_track_caller+0x1e5/0x200
>     Apr 12 11:31:38 testmachine kernel: kmemdup+0x20/0x50
>     Apr 12 11:31:38 testmachine kernel: nla_memdup_cookie+0x55/0x90
>     Apr 12 11:31:38 testmachine kernel: tcf_action_init_1+0xcc/0x230
>     Apr 12 11:31:38 testmachine kernel: tcf_exts_validate+0x52/0x110
>     Apr 12 11:31:38 testmachine kernel: basic_change+0x194/0x4d2 [cls_basic]
>     Apr 12 11:31:38 testmachine kernel: tc_ctl_tfilter+0x54d/0x9a0
>     Apr 12 11:31:38 testmachine kernel: rtnetlink_rcv_msg+0xe6/0x210
>     Apr 12 11:31:38 testmachine kernel: ? __kmalloc_node_track_caller+0x1f0/0x2a0
>     Apr 12 11:31:38 testmachine kernel: ? __alloc_skb+0x87/0x1e0
>     Apr 12 11:31:38 testmachine kernel: ? rtnl_newlink+0x860/0x860
>     Apr 12 11:31:38 testmachine kernel: netlink_rcv_skb+0xa4/0xc0
>     Apr 12 11:31:38 testmachine kernel: rtnetlink_rcv+0x28/0x30
>     Apr 12 11:31:38 testmachine kernel: netlink_unicast+0x18c/0x220
>     Apr 12 11:31:38 testmachine kernel: netlink_sendmsg+0x2f7/0x3b0
>     Apr 12 11:31:38 testmachine kernel: ? aa_sock_msg_perm+0x61/0x150
>     Apr 12 11:31:38 testmachine kernel: sock_sendmsg+0x38/0x50
>     Apr 12 11:31:38 testmachine kernel: ___sys_sendmsg+0x2c2/0x2d0
>     Apr 12 11:31:38 testmachine kernel: ? schedule+0x36/0x80
>     Apr 12 11:31:38 testmachine kernel: ? ptrace_stop+0x20a/0x2a0
>     Apr 12 11:31:38 testmachine kernel: ? ptrace_do_notify+0x98/0xc0
>     Apr 12 11:31:38 testmachine kernel: __sys_sendmsg+0x54/0x90
>     Apr 12 11:31:38 testmachine kernel: SyS_sendmsg+0x12/0x20
>     Apr 12 11:31:38 testmachine kernel: do_syscall_64+0x5b/0xc0
>     Apr 12 11:31:38 testmachine kernel: entry_SYSCALL64_slow_path+0x25/0x25
>     Apr 12 11:31:38 testmachine kernel: RIP: 0033:0x7f0aef7d0a77
>     Apr 12 11:31:38 testmachine kernel: RSP: 002b:00007ffe88627568 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
>     Apr 12 11:31:38 testmachine kernel: RAX: ffffffffffffffda RBX: 0000000058edf3fc RCX: 00007f0aef7d0a77
>     Apr 12 11:31:38 testmachine kernel: RDX: 0000000000000000 RSI: 00007ffe886275b0 RDI: 0000000000000003
>     Apr 12 11:31:38 testmachine kernel: RBP: 00007ffe886275b0 R08: 0000000000000001 R09: 0000000000000050
>     Apr 12 11:31:38 testmachine kernel: R10: 00000000000005e9 R11: 0000000000000246 R12: 00007ffe886275f0
>     Apr 12 11:31:38 testmachine kernel: R13: 00005619ea31ee00 R14: 00007ffe8862f690 R15: 0000000000000000
>     Apr 12 11:31:38 testmachine kernel: ---[ end trace be009b606808485e ]---
> 
> Which would later on be followed by different kinds of hangups,
> sometimes with more seemingly unrelated crash dumps such as:
> 
>     Apr 12 11:38:50 testmachine kernel: general protection fault: 0000 [#1] SMP
>     Apr 12 11:38:50 testmachine kernel: Modules linked in: act_police cls_basic sch_ingress veth nfsv3 nfs_acl nfs lockd grace ip6t_REJECT nf_reject_ipv6 nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables xt_mac ipt_REJECT nf_reject_ipv4 xt_physdev xt_comment nf_conntrack_ipv4 nf_defrag_ipv4 xt_tcpudp xt_mark xt_set xt_addrtype xt_multiport xt_conntrack nf_conntrack ip_set_hash_net ip_set arc4 md4 nls_utf8 cifs ccm fscache ipta
>     Apr 12 11:38:50 testmachine kernel: snd_hda_codec_realtek snd_hda_codec_generic aesni_intel aes_x86_64 crypto_simd drm_kms_helper glue_helper cryptd drm snd_hda_intel intel_cstate snd_hda_codec i2c_algo_bit fb_sys_fops snd_hda_core joydev syscopyarea snd_hwdep sysfillrect input_leds sysimgblt intel_rapl_perf snd_pcm snd_timer snd pcspkr soundcore mei_me lpc_ich mei shpchp tpm_infineon mac_hid wmi acpi_pad video vhost_net vhost macv
>     Apr 12 11:38:50 testmachine kernel: CPU: 7 PID: 4829 Comm: chromium Tainted: P W O 4.10.5-1-pve #1
>     Apr 12 11:38:50 testmachine kernel: Hardware name: ASUS All Series/Z97-A, BIOS 2801 11/11/2015
>     Apr 12 11:38:50 testmachine kernel: task: ffff93679b132d00 task.stack: ffffa479a0e00000
>     Apr 12 11:38:50 testmachine kernel: RIP: 0010:kmem_cache_alloc_trace+0x7b/0x190
>     Apr 12 11:38:50 testmachine kernel: RSP: 0018:ffffa479a0e03ad0 EFLAGS: 00010202
>     Apr 12 11:38:50 testmachine kernel: RAX: 0000000000000000 RBX: 00000000014000c0 RCX: 0000000000005291
>     Apr 12 11:38:50 testmachine kernel: RDX: 0000000000005290 RSI: 00000000014000c0 RDI: 000000000001c5c0
>     Apr 12 11:38:50 testmachine kernel: RBP: ffffa479a0e03b00 R08: ffff9367bfbdc5c0 R09: ffff936724698580
>     Apr 12 11:38:50 testmachine kernel: R10: 0017ffffc0040038 R11: 0000000000000007 R12: 00000000014000c0
>     Apr 12 11:38:50 testmachine kernel: R13: ffff93679f003b80 R14: ffffffffc0b9090f R15: ffff93679f003b80
>     Apr 12 11:38:50 testmachine kernel: FS: 00007f5a069c4040(0000) GS:ffff9367bfbc0000(0000) knlGS:0000000000000000
>     Apr 12 11:38:50 testmachine kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>     Apr 12 11:38:50 testmachine kernel: CR2: 00007f5a068de000 CR3: 00000007ccb8b000 CR4: 00000000001426e0
>     Apr 12 11:38:50 testmachine kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>     Apr 12 11:38:50 testmachine kernel: DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>     Apr 12 11:38:50 testmachine kernel: Call Trace:
>     Apr 12 11:38:50 testmachine kernel: i915_gem_object_get_pages_internal+0x6f/0x250 [i915]
>     Apr 12 11:38:50 testmachine kernel: ? kmem_cache_alloc+0x185/0x1a0
>     Apr 12 11:38:50 testmachine kernel: ____i915_gem_object_get_pages+0x20/0x60 [i915]
>     Apr 12 11:38:50 testmachine kernel: __i915_gem_object_get_pages+0x52/0x60 [i915]
>     Apr 12 11:38:50 testmachine kernel: i915_gem_batch_pool_get+0x11d/0x180 [i915]
>     Apr 12 11:38:50 testmachine kernel: i915_gem_do_execbuffer.isra.38+0x1027/0x1790 [i915]
>     Apr 12 11:38:50 testmachine kernel: ? shmem_getpage_gfp+0xf9/0xc20
>     Apr 12 11:38:50 testmachine kernel: i915_gem_execbuffer2+0xc5/0x240 [i915]
>     Apr 12 11:38:50 testmachine kernel: drm_ioctl+0x21b/0x4c0 [drm]
>     Apr 12 11:38:50 testmachine kernel: ? i915_gem_execbuffer+0x310/0x310 [i915]
>     Apr 12 11:38:50 testmachine kernel: ? __seccomp_filter+0x67/0x250
>     Apr 12 11:38:50 testmachine kernel: do_vfs_ioctl+0xa3/0x610
>     Apr 12 11:38:50 testmachine kernel: ? __secure_computing+0x3f/0xd0
>     Apr 12 11:38:50 testmachine kernel: ? syscall_trace_enter+0xcd/0x2e0
>     Apr 12 11:38:50 testmachine kernel: SyS_ioctl+0x79/0x90
>     Apr 12 11:38:50 testmachine kernel: do_syscall_64+0x5b/0xc0
>     Apr 12 11:38:50 testmachine kernel: entry_SYSCALL64_slow_path+0x25/0x25
>     Apr 12 11:38:50 testmachine kernel: RIP: 0033:0x7f59fba67ca7
>     Apr 12 11:38:50 testmachine kernel: RSP: 002b:00007ffd39778868 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
>     Apr 12 11:38:50 testmachine kernel: RAX: ffffffffffffffda RBX: 000024e398f52800 RCX: 00007f59fba67ca7
>     Apr 12 11:38:50 testmachine kernel: RDX: 00007ffd397788b0 RSI: 0000000040406469 RDI: 00000000000000a4
>     Apr 12 11:38:50 testmachine kernel: RBP: 00007ffd397788b0 R08: 0000000000000000 R09: 0000000000000000
>     Apr 12 11:38:50 testmachine kernel: R10: 0000000000000000 R11: 0000000000000246 R12: 0000000040406469
>     Apr 12 11:38:50 testmachine kernel: R13: 00000000000000a4 R14: 000024e399dd82c0 R15: 0000000000000070
>     Apr 12 11:38:50 testmachine kernel: Code: 08 65 4c 03 05 e7 de 9e 68 49 83 78 10 00 4d 8b 10 0f 84 e0 00 00 00 4d 85 d2 0f 84 d7 00 00 00 49 63 47 20 49 8b 3f 48 8d 4a 01 <49> 8b 1c 02 4c 89 d0 65 48 0f c7 0f 0f 94 c0 84 c0 74 bb 49 63
>     Apr 12 11:38:50 testmachine kernel: RIP: kmem_cache_alloc_trace+0x7b/0x190 RSP: ffffa479a0e03ad0
>     Apr 12 11:38:50 testmachine kernel: general protection fault: 0000 [#2] SMP
>     Apr 12 11:38:50 testmachine kernel: general protection fault: 0000 [#3] SMP
> 
> or:
> 
>     Apr 12 09:19:35 testmachine kernel: BUG: unable to handle kernel NULL pointer dereference at 000000000000019c
>     Apr 12 09:19:35 testmachine kernel: IP: __free_pages+0x5/0x30
>     Apr 12 09:19:35 testmachine kernel: PGD 0
>     Apr 12 09:19:35 testmachine kernel:
>     Apr 12 09:19:35 testmachine kernel: Oops: 0002 [#1] SMP
>     Apr 12 09:19:35 testmachine kernel: Modules linked in: act_police cls_basic sch_ingress veth nfsv3 nfs_acl nfs lockd grace ip6t_REJECT nf_reject_ipv6 nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables xt_mac ipt_REJECT nf_reject_ipv4 xt_physdev xt_comment nf_conntrack_ipv4 nf_defrag_ipv4 xt_tcpudp xt_mark xt_set xt_addrtype xt_multiport xt_conntrack nf_conntrack ip_set_hash_net ip_set arc4 md4 nls_utf8 cifs ccm fscache ipta
>     Apr 12 09:19:35 testmachine kernel: aes_x86_64 crypto_simd glue_helper cryptd intel_cstate snd_hda_codec_realtek snd_hda_codec_generic i915 intel_rapl_perf snd_hda_intel drm_kms_helper input_leds joydev snd_hda_codec drm snd_hda_core snd_hwdep i2c_algo_bit fb_sys_fops snd_pcm syscopyarea snd_timer sysfillrect sysimgblt snd soundcore mei_me shpchp lpc_ich mei pcspkr tpm_infineon wmi video mac_hid acpi_pad vhost_net vhost macvtap mac
>     Apr 12 09:19:35 testmachine kernel: CPU: 2 PID: 69 Comm: kworker/2:1 Tainted: P W O 4.10.5-1-pve #1
>     Apr 12 09:19:35 testmachine kernel: Hardware name: ASUS All Series/Z97-A, BIOS 2801 11/11/2015
>     Apr 12 09:19:35 testmachine kernel: Workqueue: events __i915_gem_free_work [i915]
>     Apr 12 09:19:35 testmachine kernel: task: ffff88885b134380 task.stack: ffffa7e243410000
>     Apr 12 09:19:35 testmachine kernel: RIP: 0010:__free_pages+0x5/0x30
>     Apr 12 09:19:35 testmachine kernel: RSP: 0018:ffffa7e243413d18 EFLAGS: 00010206
>     Apr 12 09:19:35 testmachine kernel: RAX: 00000000000ffff8 RBX: ffff888762473460 RCX: ffff888762473470
>     Apr 12 09:19:35 testmachine kernel: RDX: ffff888762473460 RSI: 0000000000000014 RDI: 0000000000000180
>     Apr 12 09:19:35 testmachine kernel: RBP: ffffa7e243413d38 R08: 0000000000000000 R09: 0000000000000000
>     Apr 12 09:19:35 testmachine kernel: R10: ffff8887dd8c1080 R11: 0000000000000000 R12: ffff8887624738f0
>     Apr 12 09:19:35 testmachine kernel: R13: 00000000ffffffff R14: ffff8887dd8c0440 R15: 0000000000000000
>     Apr 12 09:19:35 testmachine kernel: FS: 0000000000000000(0000) GS:ffff88887fa80000(0000) knlGS:0000000000000000
>     Apr 12 09:19:35 testmachine kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>     Apr 12 09:19:35 testmachine kernel: CR2: 000000000000019c CR3: 0000000476e09000 CR4: 00000000001426e0
>     Apr 12 09:19:35 testmachine kernel: DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>     Apr 12 09:19:35 testmachine kernel: DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>     Apr 12 09:19:35 testmachine kernel: Call Trace:
>     Apr 12 09:19:35 testmachine kernel: ? internal_free_pages+0x40/0x80 [i915]
>     Apr 12 09:19:35 testmachine kernel: i915_gem_object_put_pages_internal+0x1f/0x30 [i915]
>     Apr 12 09:19:35 testmachine kernel: __i915_gem_object_put_pages.part.62+0x11d/0x180 [i915]
>     Apr 12 09:19:35 testmachine kernel: ? dma_fence_context_alloc+0x20/0x20
>     Apr 12 09:19:35 testmachine kernel: __i915_gem_free_objects+0x161/0x330 [i915]
>     Apr 12 09:19:35 testmachine kernel: __i915_gem_free_work+0x33/0x50 [i915]
>     Apr 12 09:19:35 testmachine kernel: process_one_work+0x1fc/0x4b0
>     Apr 12 09:19:35 testmachine kernel: worker_thread+0x4b/0x500
>     Apr 12 09:19:35 testmachine kernel: kthread+0x101/0x140
>     Apr 12 09:19:35 testmachine kernel: ? process_one_work+0x4b0/0x4b0
>     Apr 12 09:19:35 testmachine kernel: ? kthread_create_on_node+0x60/0x60
>     Apr 12 09:19:35 testmachine kernel: ret_from_fork+0x2c/0x40
>     Apr 12 09:19:35 testmachine kernel: Code: ff 41 b8 05 00 00 00 31 c9 4c 89 ea 4c 89 fe e8 a2 e0 ff ff e9 1e ff ff ff 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 <f0> ff 4f 1c 75 0e 55 85 f6 48 89 e5 74 08 e8 48 e4 ff ff 5d f3
>     Apr 12 09:19:35 testmachine kernel: RIP: __free_pages+0x5/0x30 RSP: ffffa7e243413d18
>     Apr 12 09:19:35 testmachine kernel: CR2: 000000000000019c
>     Apr 12 09:19:35 testmachine kernel: ---[ end trace 89cb022ec57f7bd1 ]---
> 
> Wolfgang Bumiller (2):
>   net sched actions: fix access to uninitialized data
>   net sched actions: decrement module refcount earlier
> 
>  net/sched/act_api.c | 19 ++++++++++---------
>  1 file changed, 10 insertions(+), 9 deletions(-)
> 
I'll be happy to re-review these once these land upstream and we have an
upstream commit id to work against.

Colin




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