a447da7d00
syzkaller managed to trigger a use-after-free in tls like the
following:
BUG: KASAN: use-after-free in tls_push_record.constprop.15+0x6a2/0x810 [tls]
Write of size 1 at addr ffff88037aa08000 by task a.out/2317
CPU: 3 PID: 2317 Comm: a.out Not tainted 4.17.0+ #144
Hardware name: LENOVO 20FBCTO1WW/20FBCTO1WW, BIOS N1FET47W (1.21 ) 11/28/2016
Call Trace:
dump_stack+0x71/0xab
print_address_description+0x6a/0x280
kasan_report+0x258/0x380
? tls_push_record.constprop.15+0x6a2/0x810 [tls]
tls_push_record.constprop.15+0x6a2/0x810 [tls]
tls_sw_push_pending_record+0x2e/0x40 [tls]
tls_sk_proto_close+0x3fe/0x710 [tls]
? tcp_check_oom+0x4c0/0x4c0
? tls_write_space+0x260/0x260 [tls]
? kmem_cache_free+0x88/0x1f0
inet_release+0xd6/0x1b0
__sock_release+0xc0/0x240
sock_close+0x11/0x20
__fput+0x22d/0x660
task_work_run+0x114/0x1a0
do_exit+0x71a/0x2780
? mm_update_next_owner+0x650/0x650
? handle_mm_fault+0x2f5/0x5f0
? __do_page_fault+0x44f/0xa50
? mm_fault_error+0x2d0/0x2d0
do_group_exit+0xde/0x300
__x64_sys_exit_group+0x3a/0x50
do_syscall_64+0x9a/0x300
? page_fault+0x8/0x30
entry_SYSCALL_64_after_hwframe+0x44/0xa9
This happened through fault injection where aead_req allocation in
tls_do_encryption() eventually failed and we returned -ENOMEM from
the function. Turns out that the use-after-free is triggered from
tls_sw_sendmsg() in the second tls_push_record(). The error then
triggers a jump to waiting for memory in sk_stream_wait_memory()
resp. returning immediately in case of MSG_DONTWAIT. What follows is
the trim_both_sgl(sk, orig_size), which drops elements from the sg
list added via tls_sw_sendmsg(). Now the use-after-free gets triggered
when the socket is being closed, where tls_sk_proto_close() callback
is invoked. The tls_complete_pending_work() will figure that there's
a pending closed tls record to be flushed and thus calls into the
tls_push_pending_closed_record() from there. ctx->push_pending_record()
is called from the latter, which is the tls_sw_push_pending_record()
from sw path. This again calls into tls_push_record(). And here the
tls_fill_prepend() will panic since the buffer address has been freed
earlier via trim_both_sgl(). One way to fix it is to move the aead
request allocation out of tls_do_encryption() early into tls_push_record().
This means we don't prep the tls header and advance state to the
TLS_PENDING_CLOSED_RECORD before allocation which could potentially
fail happened. That fixes the issue on my side.
Fixes:
|
||
|---|---|---|
| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| 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 | ||
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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.