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Jiri Benc de76ae9ea1 ipv6: fix race condition between ipv6_get_ifaddr and ipv6_del_addr [ Upstream commit `7633c4da91` ] Although ipv6_get_ifaddr walks inet6_addr_lst under the RCU lock, it still means hlist_for_each_entry_rcu can return an item that got removed from the list. The memory itself of such item is not freed thanks to RCU but nothing guarantees the actual content of the memory is sane. In particular, the reference count can be zero. This can happen if ipv6_del_addr is called in parallel. ipv6_del_addr removes the entry from inet6_addr_lst (hlist_del_init_rcu(&ifp->addr_lst)) and drops all references (__in6_ifa_put(ifp) + in6_ifa_put(ifp)). With bad enough timing, this can happen: 1. In ipv6_get_ifaddr, hlist_for_each_entry_rcu returns an entry. 2. Then, the whole ipv6_del_addr is executed for the given entry. The reference count drops to zero and kfree_rcu is scheduled. 3. ipv6_get_ifaddr continues and tries to increments the reference count (in6_ifa_hold). 4. The rcu is unlocked and the entry is freed. 5. The freed entry is returned. Prevent increasing of the reference count in such case. The name in6_ifa_hold_safe is chosen to mimic the existing fib6_info_hold_safe. [ 41.506330] refcount_t: addition on 0; use-after-free. [ 41.506760] WARNING: CPU: 0 PID: 595 at lib/refcount.c:25 refcount_warn_saturate+0xa5/0x130 [ 41.507413] Modules linked in: veth bridge stp llc [ 41.507821] CPU: 0 PID: 595 Comm: python3 Not tainted 6.9.0-rc2.main-00208-g49563be82afa #14 [ 41.508479] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) [ 41.509163] RIP: 0010:refcount_warn_saturate+0xa5/0x130 [ 41.509586] Code: ad ff 90 0f 0b 90 90 c3 cc cc cc cc 80 3d c0 30 ad 01 00 75 a0 c6 05 b7 30 ad 01 01 90 48 c7 c7 38 cc 7a 8c e8 cc 18 ad ff 90 <0f> 0b 90 90 c3 cc cc cc cc 80 3d 98 30 ad 01 00 0f 85 75 ff ff ff [ 41.510956] RSP: 0018:ffffbda3c026baf0 EFLAGS: 00010282 [ 41.511368] RAX: 0000000000000000 RBX: ffff9e9c46914800 RCX: 0000000000000000 [ 41.511910] RDX: ffff9e9c7ec29c00 RSI: ffff9e9c7ec1c900 RDI: ffff9e9c7ec1c900 [ 41.512445] RBP: ffff9e9c43660c9c R08: 0000000000009ffb R09: 00000000ffffdfff [ 41.512998] R10: 00000000ffffdfff R11: ffffffff8ca58a40 R12: ffff9e9c4339a000 [ 41.513534] R13: 0000000000000001 R14: ffff9e9c438a0000 R15: ffffbda3c026bb48 [ 41.514086] FS: 00007fbc4cda1740(0000) GS:ffff9e9c7ec00000(0000) knlGS:0000000000000000 [ 41.514726] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 41.515176] CR2: 000056233b337d88 CR3: 000000000376e006 CR4: 0000000000370ef0 [ 41.515713] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 41.516252] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 41.516799] Call Trace: [ 41.517037] <TASK> [ 41.517249] ? __warn+0x7b/0x120 [ 41.517535] ? refcount_warn_saturate+0xa5/0x130 [ 41.517923] ? report_bug+0x164/0x190 [ 41.518240] ? handle_bug+0x3d/0x70 [ 41.518541] ? exc_invalid_op+0x17/0x70 [ 41.520972] ? asm_exc_invalid_op+0x1a/0x20 [ 41.521325] ? refcount_warn_saturate+0xa5/0x130 [ 41.521708] ipv6_get_ifaddr+0xda/0xe0 [ 41.522035] inet6_rtm_getaddr+0x342/0x3f0 [ 41.522376] ? __pfx_inet6_rtm_getaddr+0x10/0x10 [ 41.522758] rtnetlink_rcv_msg+0x334/0x3d0 [ 41.523102] ? netlink_unicast+0x30f/0x390 [ 41.523445] ? __pfx_rtnetlink_rcv_msg+0x10/0x10 [ 41.523832] netlink_rcv_skb+0x53/0x100 [ 41.524157] netlink_unicast+0x23b/0x390 [ 41.524484] netlink_sendmsg+0x1f2/0x440 [ 41.524826] __sys_sendto+0x1d8/0x1f0 [ 41.525145] __x64_sys_sendto+0x1f/0x30 [ 41.525467] do_syscall_64+0xa5/0x1b0 [ 41.525794] entry_SYSCALL_64_after_hwframe+0x72/0x7a [ 41.526213] RIP: 0033:0x7fbc4cfcea9a [ 41.526528] Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb b8 0f 1f 00 f3 0f 1e fa 41 89 ca 64 8b 04 25 18 00 00 00 85 c0 75 15 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 7e c3 0f 1f 44 00 00 41 54 48 83 ec 30 44 89 [ 41.527942] RSP: 002b:00007ffcf54012a8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c [ 41.528593] RAX: ffffffffffffffda RBX: 00007ffcf5401368 RCX: 00007fbc4cfcea9a [ 41.529173] RDX: 000000000000002c RSI: 00007fbc4b9d9bd0 RDI: 0000000000000005 [ 41.529786] RBP: 00007fbc4bafb040 R08: 00007ffcf54013e0 R09: 000000000000000c [ 41.530375] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 [ 41.530977] R13: ffffffffc4653600 R14: 0000000000000001 R15: 00007fbc4ca85d1b [ 41.531573] </TASK> Fixes: `5c578aedcb` ("IPv6: convert addrconf hash list to RCU") Reviewed-by: Eric Dumazet <edumazet@google.com> Reviewed-by: David Ahern <dsahern@kernel.org> Signed-off-by: Jiri Benc <jbenc@redhat.com> Link: https://lore.kernel.org/r/8ab821e36073a4a406c50ec83c9e8dc586c539e4.1712585809.git.jbenc@redhat.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>		2024-04-17 11:18:24 +02:00
Documentation	x86/bhi: Mitigate KVM by default	2024-04-10 16:28:35 +02:00
LICENSES	LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers	2021-12-16 14:33:10 +01:00
arch	arm64: dts: imx8-ss-conn: fix usdhc wrong lpcg clock order	2024-04-17 11:18:23 +02:00
block	block: prevent division by zero in blk_rq_stat_sum()	2024-04-13 13:05:12 +02:00
certs	certs: Fix build error when PKCS#11 URI contains semicolon	2023-02-09 11:28:11 +01:00
crypto	crypto: jitter - fix CRYPTO_JITTERENTROPY help text	2024-03-26 18:20:50 -04:00
drivers	octeontx2-af: Fix NIX SQ mode and BP config	2024-04-17 11:18:24 +02:00
fs	smb3: fix Open files on server counter going negative	2024-04-17 11:18:22 +02:00
include	ipv6: fix race condition between ipv6_get_ifaddr and ipv6_del_addr	2024-04-17 11:18:24 +02:00
init	init: open /initrd.image with O_LARGEFILE	2024-04-03 15:19:47 +02:00
io_uring	io_uring: clear opcode specific data for an early failure	2024-04-13 13:05:20 +02:00
ipc	ipc: fix memory leak in init_mqueue_fs()	2022-12-31 13:32:01 +01:00
kernel	PM: s2idle: Make sure CPUs will wakeup directly on resume	2024-04-17 11:18:22 +02:00
lib	pci_iounmap(): Fix MMIO mapping leak	2024-04-03 15:19:25 +02:00
mm	x86/mm/pat: fix VM_PAT handling in COW mappings	2024-04-10 16:28:33 +02:00
net	ipv6: fix race condition between ipv6_get_ifaddr and ipv6_del_addr	2024-04-17 11:18:24 +02:00
rust	rust: allocator: Prevent mis-aligned allocation	2023-08-11 12:08:18 +02:00
samples	work around gcc bugs with 'asm goto' with outputs	2024-02-23 09:12:28 +01:00
scripts	gcc-plugins/stackleak: Avoid .head.text section	2024-04-13 13:05:23 +02:00
security	landlock: Warn once if a Landlock action is requested while disabled	2024-04-03 15:19:32 +02:00
sound	ASoC: soc-core.c: Skip dummy codec when adding platforms	2024-04-13 13:05:19 +02:00
tools	tools: iio: replace seekdir() in iio_generic_buffer	2024-04-13 13:05:16 +02:00
usr	usr/gen_init_cpio.c: remove unnecessary -1 values from int file	2022-10-03 14:21:44 -07:00
virt	KVM: Always flush async #PF workqueue when vCPU is being destroyed	2024-04-03 15:19:25 +02:00
.clang-format	inet: ping: use hlist_nulls rcu iterator during lookup	2022-12-01 12:42:46 +01:00
.cocciconfig	…
.get_maintainer.ignore	get_maintainer: add Alan to .get_maintainer.ignore	2022-08-20 15:17:44 -07:00
.gitattributes	…
.gitignore	Kbuild: add Rust support	2022-09-28 09:02:20 +02:00
.mailmap	9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address	2022-12-10 17:10:52 -08:00
.rustfmt.toml	rust: add `.rustfmt.toml`	2022-09-28 09:02:20 +02:00
COPYING	…
CREDITS	MAINTAINERS: Remove Michal Marek from Kbuild maintainers	2022-11-16 14:53:00 +09:00
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	trace: Relocate event helper files	2024-03-06 14:45:17 +00:00
Makefile	Linux 6.1.86	2024-04-13 13:05:29 +02:00
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.

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.