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Lin Ma 361b6889ae net/handshake: remove fput() that causes use-after-free A reference underflow is found in TLS handshake subsystem that causes a direct use-after-free. Part of the crash log is like below: [ 2.022114] ------------[ cut here ]------------ [ 2.022193] refcount_t: underflow; use-after-free. [ 2.022288] WARNING: CPU: 0 PID: 60 at lib/refcount.c:28 refcount_warn_saturate+0xbe/0x110 [ 2.022432] Modules linked in: [ 2.022848] RIP: 0010:refcount_warn_saturate+0xbe/0x110 [ 2.023231] RSP: 0018:ffffc900001bfe18 EFLAGS: 00000286 [ 2.023325] RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00000000ffffdfff [ 2.023438] RDX: 0000000000000000 RSI: 00000000ffffffea RDI: 0000000000000001 [ 2.023555] RBP: ffff888004c20098 R08: ffffffff82b392c8 R09: 00000000ffffdfff [ 2.023693] R10: ffffffff82a592e0 R11: ffffffff82b092e0 R12: ffff888004c200d8 [ 2.023813] R13: 0000000000000000 R14: ffff888004c20000 R15: ffffc90000013ca8 [ 2.023930] FS: 0000000000000000(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000 [ 2.024062] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 2.024161] CR2: ffff888003601000 CR3: 0000000002a2e000 CR4: 00000000000006f0 [ 2.024275] Call Trace: [ 2.024322] <TASK> [ 2.024367] ? __warn+0x7f/0x130 [ 2.024430] ? refcount_warn_saturate+0xbe/0x110 [ 2.024513] ? report_bug+0x199/0x1b0 [ 2.024585] ? handle_bug+0x3c/0x70 [ 2.024676] ? exc_invalid_op+0x18/0x70 [ 2.024750] ? asm_exc_invalid_op+0x1a/0x20 [ 2.024830] ? refcount_warn_saturate+0xbe/0x110 [ 2.024916] ? refcount_warn_saturate+0xbe/0x110 [ 2.024998] __tcp_close+0x2f4/0x3d0 [ 2.025065] ? __pfx_kunit_generic_run_threadfn_adapter+0x10/0x10 [ 2.025168] tcp_close+0x1f/0x70 [ 2.025231] inet_release+0x33/0x60 [ 2.025297] sock_release+0x1f/0x80 [ 2.025361] handshake_req_cancel_test2+0x100/0x2d0 [ 2.025457] kunit_try_run_case+0x4c/0xa0 [ 2.025532] kunit_generic_run_threadfn_adapter+0x15/0x20 [ 2.025644] kthread+0xe1/0x110 [ 2.025708] ? __pfx_kthread+0x10/0x10 [ 2.025780] ret_from_fork+0x2c/0x50 One can enable CONFIG_NET_HANDSHAKE_KUNIT_TEST config to reproduce above crash. The root cause of this bug is that the commit `1ce77c998f` ("net/handshake: Unpin sock->file if a handshake is cancelled") adds one additional fput() function. That patch claims that the fput() is used to enable sock->file to be freed even when user space never calls DONE. However, it seems that the intended DONE routine will never give an additional fput() of ths sock->file. The existing two of them are just used to balance the reference added in sockfd_lookup(). This patch revert the mentioned commit to avoid the use-after-free. The patched kernel could successfully pass the KUNIT test and boot to shell. [ 0.733613] # Subtest: Handshake API tests [ 0.734029] 1..11 [ 0.734255] KTAP version 1 [ 0.734542] # Subtest: req_alloc API fuzzing [ 0.736104] ok 1 handshake_req_alloc NULL proto [ 0.736114] ok 2 handshake_req_alloc CLASS_NONE [ 0.736559] ok 3 handshake_req_alloc CLASS_MAX [ 0.737020] ok 4 handshake_req_alloc no callbacks [ 0.737488] ok 5 handshake_req_alloc no done callback [ 0.737988] ok 6 handshake_req_alloc excessive privsize [ 0.738529] ok 7 handshake_req_alloc all good [ 0.739036] # req_alloc API fuzzing: pass:7 fail:0 skip:0 total:7 [ 0.739444] ok 1 req_alloc API fuzzing [ 0.740065] ok 2 req_submit NULL req arg [ 0.740436] ok 3 req_submit NULL sock arg [ 0.740834] ok 4 req_submit NULL sock->file [ 0.741236] ok 5 req_lookup works [ 0.741621] ok 6 req_submit max pending [ 0.741974] ok 7 req_submit multiple [ 0.742382] ok 8 req_cancel before accept [ 0.742764] ok 9 req_cancel after accept [ 0.743151] ok 10 req_cancel after done [ 0.743510] ok 11 req_destroy works [ 0.743882] # Handshake API tests: pass:11 fail:0 skip:0 total:11 [ 0.744205] # Totals: pass:17 fail:0 skip:0 total:17 Acked-by: Chuck Lever <chuck.lever@oracle.com> Fixes: `1ce77c998f` ("net/handshake: Unpin sock->file if a handshake is cancelled") Signed-off-by: Lin Ma <linma@zju.edu.cn> Link: https://lore.kernel.org/r/20230613083204.633896-1-linma@zju.edu.cn Link: https://lore.kernel.org/r/20230614015249.987448-1-linma@zju.edu.cn Signed-off-by: Jakub Kicinski <kuba@kernel.org>		2023-06-14 22:26:37 -07:00
arch	ARM:	2023-06-04 07:16:53 -04:00
block	block: fix revalidate performance regression	2023-05-29 08:40:32 -06:00
certs	KEYS: Add missing function documentation	2023-04-24 16:15:52 +03:00
crypto	KEYS: asymmetric: Copy sig and digest in public_key_verify_signature()	2023-06-02 15:36:23 +02:00
Documentation	Networking fixes for 6.4-rc6, including fixes from can, wifi, netfilter,	2023-06-08 09:27:19 -07:00
drivers	A couple of straggler fixes, mostly in the stack:	2023-06-14 21:28:59 -07:00
fs	xfs: fixes for 6.4-rc5	2023-06-08 08:46:58 -07:00
include	net/sched: qdisc_destroy() old ingress and clsact Qdiscs before grafting	2023-06-14 10:31:39 +02:00
init	Objtool changes for v6.4:	2023-04-28 14:02:54 -07:00
io_uring	io_uring: undeprecate epoll_ctl support	2023-05-26 20:22:41 -06:00
ipc	Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2023-02-24 19:20:07 -08:00
kernel	Networking fixes for 6.4-rc6, including fixes from can, wifi, netfilter,	2023-06-08 09:27:19 -07:00
lib	Networking fixes for 6.4-rc6, including fixes from can, wifi, netfilter,	2023-06-08 09:27:19 -07:00
LICENSES	LICENSES: Add the copyleft-next-0.3.1 license	2022-11-08 15:44:01 +01:00
mm	mm: page_table_check: Ensure user pages are not slab pages	2023-05-29 16:14:28 +01:00
net	net/handshake: remove fput() that causes use-after-free	2023-06-14 22:26:37 -07:00
rust	Rust changes for v6.4	2023-04-30 11:20:22 -07:00
samples	samples/bpf: Drop unnecessary fallthrough	2023-05-16 19:44:05 +02:00
scripts	Locking changes in v6.4:	2023-05-05 12:56:55 -07:00
security	selinux: don't use make's grouped targets feature yet	2023-06-01 13:56:13 -04:00
sound	ALSA: hda/realtek: Enable headset onLenovo M70/M90	2023-05-24 14:18:59 +02:00
tools	selftests: forwarding: hw_stats_l3: Set addrgenmode in a separate step	2023-06-14 12:40:02 +02:00
usr	initramfs: Check negative timestamp to prevent broken cpio archive	2023-04-16 17:37:01 +09:00
virt	KVM: Fix vcpu_array[0] races	2023-05-19 13:56:26 -04:00
.clang-format	cxl for v6.4	2023-04-30 11:51:51 -07:00
.cocciconfig
.get_maintainer.ignore	get_maintainer: add Alan to .get_maintainer.ignore	2022-08-20 15:17:44 -07:00
.gitattributes	.gitattributes: use 'dts' diff driver for *.dtso files	2023-02-26 15:28:23 +09:00
.gitignore	linux-kselftest-kunit-6.4-rc1	2023-04-24 12:31:32 -07:00
.mailmap	mailmap: add entries for Nikolay Aleksandrov	2023-05-17 09:35:05 +01:00
.rustfmt.toml	rust: add `.rustfmt.toml`	2022-09-28 09:02:20 +02:00
COPYING	COPYING: state that all contributions really are covered by this file	2020-02-10 13:32:20 -08:00
CREDITS	MAINTAINERS: sctp: move Neil to CREDITS	2023-05-12 08:51:32 +01:00
Kbuild	Kbuild updates for v6.1	2022-10-10 12:00:45 -07:00
Kconfig	kbuild: ensure full rebuild when the compiler is updated	2020-05-12 13:28:33 +09:00
MAINTAINERS	MAINTAINERS: Add entry for debug objects	2023-06-07 12:21:30 -07:00
Makefile	Linux 6.4-rc5	2023-06-04 14:04:27 -04:00
README	Drop all 00-INDEX files from Documentation/	2018-09-09 15:08:58 -06:00

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.