linux-cve-announce - CVE-2022-50069: BPF: Fix potential bad pointer dereference in bpf_sys

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Message-ID: <2025061852-CVE-2022-50069-9dba@gregkh>
Date: Wed, 18 Jun 2025 13:02:14 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-50069: BPF: Fix potential bad pointer dereference in bpf_sys_bpf()

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

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

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

BPF: Fix potential bad pointer dereference in bpf_sys_bpf()

The bpf_sys_bpf() helper function allows an eBPF program to load another
eBPF program from within the kernel. In this case the argument union
bpf_attr pointer (as well as the insns and license pointers inside) is a
kernel address instead of a userspace address (which is the case of a
usual bpf() syscall). To make the memory copying process in the syscall
work in both cases, bpfptr_t was introduced to wrap around the pointer
and distinguish its origin. Specifically, when copying memory contents
from a bpfptr_t, a copy_from_user() is performed in case of a userspace
address and a memcpy() is performed for a kernel address.

This can lead to problems because the in-kernel pointer is never checked
for validity. The problem happens when an eBPF syscall program tries to
call bpf_sys_bpf() to load a program but provides a bad insns pointer --
say 0xdeadbeef -- in the bpf_attr union. The helper calls __sys_bpf()
which would then call bpf_prog_load() to load the program.
bpf_prog_load() is responsible for copying the eBPF instructions to the
newly allocated memory for the program; it creates a kernel bpfptr_t for
insns and invokes copy_from_bpfptr(). Internally, all bpfptr_t
operations are backed by the corresponding sockptr_t operations, which
performs direct memcpy() on kernel pointers for copy_from/strncpy_from
operations. Therefore, the code is always happy to dereference the bad
pointer to trigger a un-handle-able page fault and in turn an oops.
However, this is not supposed to happen because at that point the eBPF
program is already verified and should not cause a memory error.

Sample KASAN trace:

[   25.685056][  T228] ==================================================================
[   25.685680][  T228] BUG: KASAN: user-memory-access in copy_from_bpfptr+0x21/0x30
[   25.686210][  T228] Read of size 80 at addr 00000000deadbeef by task poc/228
[   25.686732][  T228]
[   25.686893][  T228] CPU: 3 PID: 228 Comm: poc Not tainted 5.19.0-rc7 #7
[   25.687375][  T228] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS d55cb5a 04/01/2014
[   25.687991][  T228] Call Trace:
[   25.688223][  T228]  <TASK>
[   25.688429][  T228]  dump_stack_lvl+0x73/0x9e
[   25.688747][  T228]  print_report+0xea/0x200
[   25.689061][  T228]  ? copy_from_bpfptr+0x21/0x30
[   25.689401][  T228]  ? _printk+0x54/0x6e
[   25.689693][  T228]  ? _raw_spin_lock_irqsave+0x70/0xd0
[   25.690071][  T228]  ? copy_from_bpfptr+0x21/0x30
[   25.690412][  T228]  kasan_report+0xb5/0xe0
[   25.690716][  T228]  ? copy_from_bpfptr+0x21/0x30
[   25.691059][  T228]  kasan_check_range+0x2bd/0x2e0
[   25.691405][  T228]  ? copy_from_bpfptr+0x21/0x30
[   25.691734][  T228]  memcpy+0x25/0x60
[   25.692000][  T228]  copy_from_bpfptr+0x21/0x30
[   25.692328][  T228]  bpf_prog_load+0x604/0x9e0
[   25.692653][  T228]  ? cap_capable+0xb4/0xe0
[   25.692956][  T228]  ? security_capable+0x4f/0x70
[   25.693324][  T228]  __sys_bpf+0x3af/0x580
[   25.693635][  T228]  bpf_sys_bpf+0x45/0x240
[   25.693937][  T228]  bpf_prog_f0ec79a5a3caca46_bpf_func1+0xa2/0xbd
[   25.694394][  T228]  bpf_prog_run_pin_on_cpu+0x2f/0xb0
[   25.694756][  T228]  bpf_prog_test_run_syscall+0x146/0x1c0
[   25.695144][  T228]  bpf_prog_test_run+0x172/0x190
[   25.695487][  T228]  __sys_bpf+0x2c5/0x580
[   25.695776][  T228]  __x64_sys_bpf+0x3a/0x50
[   25.696084][  T228]  do_syscall_64+0x60/0x90
[   25.696393][  T228]  ? fpregs_assert_state_consistent+0x50/0x60
[   25.696815][  T228]  ? exit_to_user_mode_prepare+0x36/0xa0
[   25.697202][  T228]  ? syscall_exit_to_user_mode+0x20/0x40
[   25.697586][  T228]  ? do_syscall_64+0x6e/0x90
[   25.697899][  T228]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
[   25.698312][  T228] RIP: 0033:0x7f6d543fb759
[   25.698624][  T228] Code: 08 5b 89 e8 5d c3 66 2e 0f 1f 84 00 00 00 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 97 a6 0e 00 f7 d8 64 89 01 48
[   25.699946][  T228] RSP: 002b:00007ffc3df78468 EFLAGS: 00000287 ORIG_RAX: 0000000000000141
[   25.700526][  T228] RAX: ffffffffffffffda RBX: 00007ffc3df78628 RCX: 00007f6d543fb759
[   25.701071][  T228] RDX: 0000000000000090 RSI: 00007ffc3df78478 RDI: 000000000000000a
[   25.701636][  T228] RBP: 00007ffc3df78510 R08: 0000000000000000 R09: 0000000000300000
[   25.702191][  T228] R10: 0000000000000005 R11: 0000000000000287 R12: 0000000000000000
[   25.702736][  T228] R13: 00007ffc3df78638 R14: 000055a1584aca68 R15: 00007f6d5456a000
[   25.703282][  T228]  </TASK>
[   25.703490][  T228] ==================================================================
[   25.704050][  T228] Disabling lock debugging due to kernel taint

Update copy_from_bpfptr() and strncpy_from_bpfptr() so that:
 - for a kernel pointer, it uses the safe copy_from_kernel_nofault() and
   strncpy_from_kernel_nofault() functions.
 - for a userspace pointer, it performs copy_from_user() and
   strncpy_from_user().

The Linux kernel CVE team has assigned CVE-2022-50069 to this issue.


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

	Issue introduced in 5.14 with commit af2ac3e13e45752af03c8a933f9b6e18841b128b and fixed in 5.15.63 with commit 41fd6cc88aaf7058b9dfc9c7a09cc80f99c8c830
	Issue introduced in 5.14 with commit af2ac3e13e45752af03c8a933f9b6e18841b128b and fixed in 5.19.4 with commit 1f6db7148ed7382b336c5827af33b5d9e992630e
	Issue introduced in 5.14 with commit af2ac3e13e45752af03c8a933f9b6e18841b128b and fixed in 6.0 with commit e2dcac2f58f5a95ab092d1da237ffdc0da1832cf

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-2022-50069
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:
	include/linux/bpfptr.h


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/41fd6cc88aaf7058b9dfc9c7a09cc80f99c8c830
	https://git.kernel.org/stable/c/1f6db7148ed7382b336c5827af33b5d9e992630e
	https://git.kernel.org/stable/c/e2dcac2f58f5a95ab092d1da237ffdc0da1832cf