linux-stable.git/net/core, branch v5.4.97

neighbour: Prevent a dead entry from updating gc_list

2021-02-10T08:25:32+00:00

commit eb4e8fac00d1e01ada5e57c05d24739156086677 upstream.

Following race condition was detected:
 - neigh_flush_dev() is under execution and calls
neigh_mark_dead(n) marking the neighbour entry 'n' as dead.

 - Executing: __netif_receive_skb() ->
__netif_receive_skb_core() -> arp_rcv() -> arp_process().arp_process()
calls __neigh_lookup() which takes a reference on neighbour entry 'n'.

 - Moves further along neigh_flush_dev() and calls
neigh_cleanup_and_release(n), but since reference count increased in t2,
'n' couldn't be destroyed.

 - Moves further along, arp_process() and calls
neigh_update()-> __neigh_update() -> neigh_update_gc_list(), which adds
the neighbour entry back in gc_list(neigh_mark_dead(), removed it
earlier in t0 from gc_list)

 - arp_process() finally calls neigh_release(n), destroying
the neighbour entry.

This leads to 'n' still being part of gc_list, but the actual
neighbour structure has been freed.

The situation can be prevented from happening if we disallow a dead
entry to have any possibility of updating gc_list. This is what the
patch intends to achieve.

Fixes: 9c29a2f55ec0 ("neighbor: Fix locking order for gc_list changes")
Signed-off-by: Chinmay Agarwal 
Reviewed-by: Cong Wang 
Reviewed-by: David Ahern 
Link: https://lore.kernel.org/r/20210127165453.GA20514@chinagar-linux.qualcomm.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

net_sched: gen_estimator: support large ewma log

2021-02-07T14:35:47+00:00

commit dd5e073381f2ada3630f36be42833c6e9c78b75e upstream

syzbot report reminded us that very big ewma_log were supported in the past,
even if they made litle sense.

tc qdisc replace dev xxx root est 1sec 131072sec ...

While fixing the bug, also add boundary checks for ewma_log, in line
with range supported by iproute2.

UBSAN: shift-out-of-bounds in net/core/gen_estimator.c:83:38
shift exponent -1 is negative
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.10.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x107/0x163 lib/dump_stack.c:120
 ubsan_epilogue+0xb/0x5a lib/ubsan.c:148
 __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:395
 est_timer.cold+0xbb/0x12d net/core/gen_estimator.c:83
 call_timer_fn+0x1a5/0x710 kernel/time/timer.c:1417
 expire_timers kernel/time/timer.c:1462 [inline]
 __run_timers.part.0+0x692/0xa80 kernel/time/timer.c:1731
 __run_timers kernel/time/timer.c:1712 [inline]
 run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1744
 __do_softirq+0x2bc/0xa77 kernel/softirq.c:343
 asm_call_irq_on_stack+0xf/0x20
 
 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline]
 run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline]
 do_softirq_own_stack+0xaa/0xd0 arch/x86/kernel/irq_64.c:77
 invoke_softirq kernel/softirq.c:226 [inline]
 __irq_exit_rcu+0x17f/0x200 kernel/softirq.c:420
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:432
 sysvec_apic_timer_interrupt+0x4d/0x100 arch/x86/kernel/apic/apic.c:1096
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:628
RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:29 [inline]
RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:79 [inline]
RIP: 0010:arch_irqs_disabled arch/x86/include/asm/irqflags.h:169 [inline]
RIP: 0010:acpi_safe_halt drivers/acpi/processor_idle.c:111 [inline]
RIP: 0010:acpi_idle_do_entry+0x1c9/0x250 drivers/acpi/processor_idle.c:516

Fixes: 1c0d32fde5bd ("net_sched: gen_estimator: complete rewrite of rate estimators")
Signed-off-by: Eric Dumazet 
Reported-by: syzbot 
Link: https://lore.kernel.org/r/20210114181929.1717985-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski 
[sudip: adjust context]
Signed-off-by: Sudip Mukherjee 
Signed-off-by: Greg Kroah-Hartman

net: Disable NETIF_F_HW_TLS_RX when RXCSUM is disabled

2021-01-27T10:47:54+00:00

commit a3eb4e9d4c9218476d05c52dfd2be3d6fdce6b91 upstream.

With NETIF_F_HW_TLS_RX packets are decrypted in HW. This cannot be
logically done when RXCSUM offload is off.

Fixes: 14136564c8ee ("net: Add TLS RX offload feature")
Signed-off-by: Tariq Toukan 
Reviewed-by: Boris Pismenny 
Link: https://lore.kernel.org/r/20210117151538.9411-1-tariqt@nvidia.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

skbuff: back tiny skbs with kmalloc() in __netdev_alloc_skb() too

2021-01-27T10:47:53+00:00

commit 66c556025d687dbdd0f748c5e1df89c977b6c02a upstream.

Commit 3226b158e67c ("net: avoid 32 x truesize under-estimation for
tiny skbs") ensured that skbs with data size lower than 1025 bytes
will be kmalloc'ed to avoid excessive page cache fragmentation and
memory consumption.
However, the fix adressed only __napi_alloc_skb() (primarily for
virtio_net and napi_get_frags()), but the issue can still be achieved
through __netdev_alloc_skb(), which is still used by several drivers.
Drivers often allocate a tiny skb for headers and place the rest of
the frame to frags (so-called copybreak).
Mirror the condition to __netdev_alloc_skb() to handle this case too.

Since v1 [0]:
 - fix "Fixes:" tag;
 - refine commit message (mention copybreak usecase).

[0] https://lore.kernel.org/netdev/20210114235423.232737-1-alobakin@pm.me

Fixes: a1c7fff7e18f ("net: netdev_alloc_skb() use build_skb()")
Signed-off-by: Alexander Lobakin 
Link: https://lore.kernel.org/r/20210115150354.85967-1-alobakin@pm.me
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

net, sctp, filter: remap copy_from_user failure error

2021-01-23T14:58:00+00:00

[ no upstream commit ]

Fix a potential kernel address leakage for the prerequisite where there is
a BPF program attached to the cgroup/setsockopt hook. The latter can only
be attached under root, however, if the attached program returns 1 to then
run the related kernel handler, an unprivileged program could probe for
kernel addresses that way. The reason this is possible is that we're under
set_fs(KERNEL_DS) when running the kernel setsockopt handler. Aside from
old cBPF there is also SCTP's struct sctp_getaddrs_old which contains
pointers in the uapi struct that further need copy_from_user() inside the
handler. In the normal case this would just return -EFAULT, but under a
temporary KERNEL_DS setting the memory would be copied and we'd end up at
a different error code, that is, -EINVAL, for both cases given subsequent
validations fail, which then allows the app to distinguish and make use of
this fact for probing the address space. In case of later kernel versions
this issue won't work anymore thanks to Christoph Hellwig's work that got
rid of the various temporary set_fs() address space overrides altogether.
One potential option for 5.4 as the only affected stable kernel with the
least complexity would be to remap those affected -EFAULT copy_from_user()
error codes with -EINVAL such that they cannot be probed anymore. Risk of
breakage should be rather low for this particular error case.

Fixes: 0d01da6afc54 ("bpf: implement getsockopt and setsockopt hooks")
Reported-by: Ryota Shiga (Flatt Security)
Signed-off-by: Daniel Borkmann 
Cc: Stanislav Fomichev 
Cc: Eric Dumazet 
Acked-by: Marcelo Ricardo Leitner 
Signed-off-by: Greg Kroah-Hartman

net: avoid 32 x truesize under-estimation for tiny skbs

2021-01-23T14:57:59+00:00

[ Upstream commit 3226b158e67cfaa677fd180152bfb28989cb2fac ]

Both virtio net and napi_get_frags() allocate skbs
with a very small skb->head

While using page fragments instead of a kmalloc backed skb->head might give
a small performance improvement in some cases, there is a huge risk of
under estimating memory usage.

For both GOOD_COPY_LEN and GRO_MAX_HEAD, we can fit at least 32 allocations
per page (order-3 page in x86), or even 64 on PowerPC

We have been tracking OOM issues on GKE hosts hitting tcp_mem limits
but consuming far more memory for TCP buffers than instructed in tcp_mem[2]

Even if we force napi_alloc_skb() to only use order-0 pages, the issue
would still be there on arches with PAGE_SIZE >= 32768

This patch makes sure that small skb head are kmalloc backed, so that
other objects in the slab page can be reused instead of being held as long
as skbs are sitting in socket queues.

Note that we might in the future use the sk_buff napi cache,
instead of going through a more expensive __alloc_skb()

Another idea would be to use separate page sizes depending
on the allocated length (to never have more than 4 frags per page)

I would like to thank Greg Thelen for his precious help on this matter,
analysing crash dumps is always a time consuming task.

Fixes: fd11a83dd363 ("net: Pull out core bits of __netdev_alloc_skb and add __napi_alloc_skb")
Signed-off-by: Eric Dumazet 
Cc: Paolo Abeni 
Cc: Greg Thelen 
Reviewed-by: Alexander Duyck 
Acked-by: Michael S. Tsirkin 
Link: https://lore.kernel.org/r/20210113161819.1155526-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

udp: Prevent reuseport_select_sock from reading uninitialized socks

2021-01-23T14:57:56+00:00

[ Upstream commit fd2ddef043592e7de80af53f47fa46fd3573086e ]

reuse->socks[] is modified concurrently by reuseport_add_sock. To
prevent reading values that have not been fully initialized, only read
the array up until the last known safe index instead of incorrectly
re-reading the last index of the array.

Fixes: acdcecc61285f ("udp: correct reuseport selection with connected sockets")
Signed-off-by: Baptiste Lepers 
Acked-by: Willem de Bruijn 
Link: https://lore.kernel.org/r/20210107051110.12247-1-baptiste.lepers@gmail.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

net: drop bogus skb with CHECKSUM_PARTIAL and offset beyond end of trimmed packet

2021-01-17T13:05:38+00:00

commit 54970a2fbb673f090b7f02d7f57b10b2e0707155 upstream.

syzbot reproduces BUG_ON in skb_checksum_help():
tun creates (bogus) skb with huge partial-checksummed area and
small ip packet inside. Then ip_rcv trims the skb based on size
of internal ip packet, after that csum offset points beyond of
trimmed skb. Then checksum_tg() called via netfilter hook
triggers BUG_ON:

        offset = skb_checksum_start_offset(skb);
        BUG_ON(offset >= skb_headlen(skb));

To work around the problem this patch forces pskb_trim_rcsum_slow()
to return -EINVAL in described scenario. It allows its callers to
drop such kind of packets.

Link: https://syzkaller.appspot.com/bug?id=b419a5ca95062664fe1a60b764621eb4526e2cd0
Reported-by: syzbot+7010af67ced6105e5ab6@syzkaller.appspotmail.com
Signed-off-by: Vasily Averin 
Acked-by: Willem de Bruijn 
Link: https://lore.kernel.org/r/1b2494af-2c56-8ee2-7bc0-923fcad1cdf8@virtuozzo.com
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

net-sysfs: take the rtnl lock when accessing xps_rxqs_map and num_tc

2021-01-12T19:16:13+00:00

[ Upstream commit 4ae2bb81649dc03dfc95875f02126b14b773f7ab ]

Accesses to dev->xps_rxqs_map (when using dev->num_tc) should be
protected by the rtnl lock, like we do for netif_set_xps_queue. I didn't
see an actual bug being triggered, but let's be safe here and take the
rtnl lock while accessing the map in sysfs.

Fixes: 8af2c06ff4b1 ("net-sysfs: Add interface for Rx queue(s) map per Tx queue")
Signed-off-by: Antoine Tenart 
Reviewed-by: Alexander Duyck 
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman

net-sysfs: take the rtnl lock when storing xps_rxqs

2021-01-12T19:16:13+00:00

[ Upstream commit 2d57b4f142e0b03e854612b8e28978935414bced ]

Two race conditions can be triggered when storing xps rxqs, resulting in
various oops and invalid memory accesses:

1. Calling netdev_set_num_tc while netif_set_xps_queue:

   - netif_set_xps_queue uses dev->tc_num as one of the parameters to
     compute the size of new_dev_maps when allocating it. dev->tc_num is
     also used to access the map, and the compiler may generate code to
     retrieve this field multiple times in the function.

   - netdev_set_num_tc sets dev->tc_num.

   If new_dev_maps is allocated using dev->tc_num and then dev->tc_num
   is set to a higher value through netdev_set_num_tc, later accesses to
   new_dev_maps in netif_set_xps_queue could lead to accessing memory
   outside of new_dev_maps; triggering an oops.

2. Calling netif_set_xps_queue while netdev_set_num_tc is running:

   2.1. netdev_set_num_tc starts by resetting the xps queues,
        dev->tc_num isn't updated yet.

   2.2. netif_set_xps_queue is called, setting up the map with the
        *old* dev->num_tc.

   2.3. netdev_set_num_tc updates dev->tc_num.

   2.4. Later accesses to the map lead to out of bound accesses and
        oops.

   A similar issue can be found with netdev_reset_tc.

One way of triggering this is to set an iface up (for which the driver
uses netdev_set_num_tc in the open path, such as bnx2x) and writing to
xps_rxqs in a concurrent thread. With the right timing an oops is
triggered.

Both issues have the same fix: netif_set_xps_queue, netdev_set_num_tc
and netdev_reset_tc should be mutually exclusive. We do that by taking
the rtnl lock in xps_rxqs_store.

Fixes: 8af2c06ff4b1 ("net-sysfs: Add interface for Rx queue(s) map per Tx queue")
Signed-off-by: Antoine Tenart 
Reviewed-by: Alexander Duyck 
Signed-off-by: Jakub Kicinski 
Signed-off-by: Greg Kroah-Hartman