037f9cdf72
netdev_upper_dev_link() is useful to manage lower/upper interfaces.
And this function internally validates looping, maximum depth.
All or most virtual interfaces that could have a real interface
(e.g. macsec, macvlan, ipvlan etc.) use lower/upper infrastructure.
Test commands:
modprobe rmnet
ip link add dummy0 type dummy
ip link add rmnet1 link dummy0 type rmnet mux_id 1
for i in {2..100}
do
let A=$i-1
ip link add rmnet$i link rmnet$A type rmnet mux_id $i
done
ip link del dummy0
The purpose of the test commands is to make stack overflow.
Splat looks like:
[ 52.411438][ T1395] BUG: KASAN: slab-out-of-bounds in find_busiest_group+0x27e/0x2c00
[ 52.413218][ T1395] Write of size 64 at addr ffff8880c774bde0 by task ip/1395
[ 52.414841][ T1395]
[ 52.430720][ T1395] CPU: 1 PID: 1395 Comm: ip Not tainted 5.6.0-rc1+ #447
[ 52.496511][ T1395] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[ 52.513597][ T1395] Call Trace:
[ 52.546516][ T1395]
[ 52.558773][ T1395] Allocated by task 3171537984:
[ 52.588290][ T1395] BUG: unable to handle page fault for address: ffffffffb999e260
[ 52.589311][ T1395] #PF: supervisor read access in kernel mode
[ 52.590529][ T1395] #PF: error_code(0x0000) - not-present page
[ 52.591374][ T1395] PGD d6818067 P4D d6818067 PUD d6819063 PMD 0
[ 52.592288][ T1395] Thread overran stack, or stack corrupted
[ 52.604980][ T1395] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI
[ 52.605856][ T1395] CPU: 1 PID: 1395 Comm: ip Not tainted 5.6.0-rc1+ #447
[ 52.611764][ T1395] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[ 52.621520][ T1395] RIP: 0010:stack_depot_fetch+0x10/0x30
[ 52.622296][ T1395] Code: ff e9 f9 fe ff ff 48 89 df e8 9c 1d 91 ff e9 ca fe ff ff cc cc cc cc cc cc cc 89 f8 0
[ 52.627887][ T1395] RSP: 0018:ffff8880c774bb60 EFLAGS: 00010006
[ 52.628735][ T1395] RAX: 00000000001f8880 RBX: ffff8880c774d140 RCX: 0000000000000000
[ 52.631773][ T1395] RDX: 000000000000001d RSI: ffff8880c774bb68 RDI: 0000000000003ff0
[ 52.649584][ T1395] RBP: ffffea00031dd200 R08: ffffed101b43e403 R09: ffffed101b43e403
[ 52.674857][ T1395] R10: 0000000000000001 R11: ffffed101b43e402 R12: ffff8880d900e5c0
[ 52.678257][ T1395] R13: ffff8880c774c000 R14: 0000000000000000 R15: dffffc0000000000
[ 52.694541][ T1395] FS: 00007fe867f6e0c0(0000) GS:ffff8880da000000(0000) knlGS:0000000000000000
[ 52.764039][ T1395] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 52.815008][ T1395] CR2: ffffffffb999e260 CR3: 00000000c26aa005 CR4: 00000000000606e0
[ 52.862312][ T1395] Call Trace:
[ 52.887133][ T1395] Modules linked in: dummy rmnet veth openvswitch nsh nf_conncount nf_nat nf_conntrack nf_dex
[ 52.936749][ T1395] CR2: ffffffffb999e260
[ 52.965695][ T1395] ---[ end trace 7e32ca99482dbb31 ]---
[ 52.966556][ T1395] RIP: 0010:stack_depot_fetch+0x10/0x30
[ 52.971083][ T1395] Code: ff e9 f9 fe ff ff 48 89 df e8 9c 1d 91 ff e9 ca fe ff ff cc cc cc cc cc cc cc 89 f8 0
[ 53.003650][ T1395] RSP: 0018:ffff8880c774bb60 EFLAGS: 00010006
[ 53.043183][ T1395] RAX: 00000000001f8880 RBX: ffff8880c774d140 RCX: 0000000000000000
[ 53.076480][ T1395] RDX: 000000000000001d RSI: ffff8880c774bb68 RDI: 0000000000003ff0
[ 53.093858][ T1395] RBP: ffffea00031dd200 R08: ffffed101b43e403 R09: ffffed101b43e403
[ 53.112795][ T1395] R10: 0000000000000001 R11: ffffed101b43e402 R12: ffff8880d900e5c0
[ 53.139837][ T1395] R13: ffff8880c774c000 R14: 0000000000000000 R15: dffffc0000000000
[ 53.141500][ T1395] FS: 00007fe867f6e0c0(0000) GS:ffff8880da000000(0000) knlGS:0000000000000000
[ 53.143343][ T1395] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 53.152007][ T1395] CR2: ffffffffb999e260 CR3: 00000000c26aa005 CR4: 00000000000606e0
[ 53.156459][ T1395] Kernel panic - not syncing: Fatal exception
[ 54.213570][ T1395] Shutting down cpus with NMI
[ 54.354112][ T1395] Kernel Offset: 0x33000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0x)
[ 54.355687][ T1395] Rebooting in 5 seconds..
Fixes: b37f78f234bf ("net: qualcomm: rmnet: Fix crash on real dev unregistration")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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.