Message-ID: <2025082234-CVE-2025-38640-e7a9@gregkh>
Date: Fri, 22 Aug 2025 18:00:48 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38640: bpf: Disable migration in nf_hook_run_bpf().

From: Greg Kroah-Hartman <gregkh@...nel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

bpf: Disable migration in nf_hook_run_bpf().

syzbot reported that the netfilter bpf prog can be called without
migration disabled in xmit path.

Then the assertion in __bpf_prog_run() fails, triggering the splat
below. [0]

Let's use bpf_prog_run_pin_on_cpu() in nf_hook_run_bpf().

[0]:
BUG: assuming non migratable context at ./include/linux/filter.h:703
in_atomic(): 0, irqs_disabled(): 0, migration_disabled() 0 pid: 5829, name: sshd-session
3 locks held by sshd-session/5829:
 #0: ffff88807b4e4218 (sk_lock-AF_INET){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1667 [inline]
 #0: ffff88807b4e4218 (sk_lock-AF_INET){+.+.}-{0:0}, at: tcp_sendmsg+0x20/0x50 net/ipv4/tcp.c:1395
 #1: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #1: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #1: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: __ip_queue_xmit+0x69/0x26c0 net/ipv4/ip_output.c:470
 #2: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #2: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #2: ffffffff8e5c4e00 (rcu_read_lock){....}-{1:3}, at: nf_hook+0xb2/0x680 include/linux/netfilter.h:241
CPU: 0 UID: 0 PID: 5829 Comm: sshd-session Not tainted 6.16.0-rc6-syzkaller-00002-g155a3c003e55 #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:120
 __cant_migrate kernel/sched/core.c:8860 [inline]
 __cant_migrate+0x1c7/0x250 kernel/sched/core.c:8834
 __bpf_prog_run include/linux/filter.h:703 [inline]
 bpf_prog_run include/linux/filter.h:725 [inline]
 nf_hook_run_bpf+0x83/0x1e0 net/netfilter/nf_bpf_link.c:20
 nf_hook_entry_hookfn include/linux/netfilter.h:157 [inline]
 nf_hook_slow+0xbb/0x200 net/netfilter/core.c:623
 nf_hook+0x370/0x680 include/linux/netfilter.h:272
 NF_HOOK_COND include/linux/netfilter.h:305 [inline]
 ip_output+0x1bc/0x2a0 net/ipv4/ip_output.c:433
 dst_output include/net/dst.h:459 [inline]
 ip_local_out net/ipv4/ip_output.c:129 [inline]
 __ip_queue_xmit+0x1d7d/0x26c0 net/ipv4/ip_output.c:527
 __tcp_transmit_skb+0x2686/0x3e90 net/ipv4/tcp_output.c:1479
 tcp_transmit_skb net/ipv4/tcp_output.c:1497 [inline]
 tcp_write_xmit+0x1274/0x84e0 net/ipv4/tcp_output.c:2838
 __tcp_push_pending_frames+0xaf/0x390 net/ipv4/tcp_output.c:3021
 tcp_push+0x225/0x700 net/ipv4/tcp.c:759
 tcp_sendmsg_locked+0x1870/0x42b0 net/ipv4/tcp.c:1359
 tcp_sendmsg+0x2e/0x50 net/ipv4/tcp.c:1396
 inet_sendmsg+0xb9/0x140 net/ipv4/af_inet.c:851
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg net/socket.c:727 [inline]
 sock_write_iter+0x4aa/0x5b0 net/socket.c:1131
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x6c7/0x1150 fs/read_write.c:686
 ksys_write+0x1f8/0x250 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe7d365d407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP:

The Linux kernel CVE team has assigned CVE-2025-38640 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.4 with commit fd9c663b9ad67dedfc9a3fd3429ddd3e83782b4d and fixed in 6.6.102 with commit ee2502485702e4398cd74dbfb288bfa111d25e62
	Issue introduced in 6.4 with commit fd9c663b9ad67dedfc9a3fd3429ddd3e83782b4d and fixed in 6.12.42 with commit 62f6175d145e00fc999fd2fcbffad3f59253c66a
	Issue introduced in 6.4 with commit fd9c663b9ad67dedfc9a3fd3429ddd3e83782b4d and fixed in 6.15.10 with commit e0199c28167a8a4adec036005a8df268b2b68529
	Issue introduced in 6.4 with commit fd9c663b9ad67dedfc9a3fd3429ddd3e83782b4d and fixed in 6.16.1 with commit 0a356da16fb933abbeeb7aea038c351f3342cd3f
	Issue introduced in 6.4 with commit fd9c663b9ad67dedfc9a3fd3429ddd3e83782b4d and fixed in 6.17-rc1 with commit 17ce3e5949bc37557305ad46316f41c7875d6366

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2025-38640
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	net/netfilter/nf_bpf_link.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/ee2502485702e4398cd74dbfb288bfa111d25e62
	https://git.kernel.org/stable/c/62f6175d145e00fc999fd2fcbffad3f59253c66a
	https://git.kernel.org/stable/c/e0199c28167a8a4adec036005a8df268b2b68529
	https://git.kernel.org/stable/c/0a356da16fb933abbeeb7aea038c351f3342cd3f
	https://git.kernel.org/stable/c/17ce3e5949bc37557305ad46316f41c7875d6366

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