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75e68e5bf2
We can end up modifying the sockhash bucket list from two CPUs when a
sockhash is being destroyed (sock_hash_free) on one CPU, while a socket
that is in the sockhash is unlinking itself from it on another CPU
it (sock_hash_delete_from_link).
This results in accessing a list element that is in an undefined state as
reported by KASAN:
| ==================================================================
| BUG: KASAN: wild-memory-access in sock_hash_free+0x13c/0x280
| Write of size 8 at addr dead000000000122 by task kworker/2:1/95
|
| CPU: 2 PID: 95 Comm: kworker/2:1 Not tainted 5.7.0-rc7-02961-ge22c35ab0038-dirty #691
| Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014
| Workqueue: events bpf_map_free_deferred
| Call Trace:
| dump_stack+0x97/0xe0
| ? sock_hash_free+0x13c/0x280
| __kasan_report.cold+0x5/0x40
| ? mark_lock+0xbc1/0xc00
| ? sock_hash_free+0x13c/0x280
| kasan_report+0x38/0x50
| ? sock_hash_free+0x152/0x280
| sock_hash_free+0x13c/0x280
| bpf_map_free_deferred+0xb2/0xd0
| ? bpf_map_charge_finish+0x50/0x50
| ? rcu_read_lock_sched_held+0x81/0xb0
| ? rcu_read_lock_bh_held+0x90/0x90
| process_one_work+0x59a/0xac0
| ? lock_release+0x3b0/0x3b0
| ? pwq_dec_nr_in_flight+0x110/0x110
| ? rwlock_bug.part.0+0x60/0x60
| worker_thread+0x7a/0x680
| ? _raw_spin_unlock_irqrestore+0x4c/0x60
| kthread+0x1cc/0x220
| ? process_one_work+0xac0/0xac0
| ? kthread_create_on_node+0xa0/0xa0
| ret_from_fork+0x24/0x30
| ==================================================================
Fix it by reintroducing spin-lock protected critical section around the
code that removes the elements from the bucket on sockhash free.
To do that we also need to defer processing of removed elements, until out
of atomic context so that we can unlink the socket from the map when
holding the sock lock.
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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.