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Message-ID: <2024122734-CVE-2024-56633-ac1d@gregkh>
Date: Fri, 27 Dec 2024 16:02:34 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-56633: tcp_bpf: Fix the sk_mem_uncharge logic in tcp_bpf_sendmsg
Description
===========
In the Linux kernel, the following vulnerability has been resolved:
tcp_bpf: Fix the sk_mem_uncharge logic in tcp_bpf_sendmsg
The current sk memory accounting logic in __SK_REDIRECT is pre-uncharging
tosend bytes, which is either msg->sg.size or a smaller value apply_bytes.
Potential problems with this strategy are as follows:
- If the actual sent bytes are smaller than tosend, we need to charge some
bytes back, as in line 487, which is okay but seems not clean.
- When tosend is set to apply_bytes, as in line 417, and (ret < 0), we may
miss uncharging (msg->sg.size - apply_bytes) bytes.
[...]
415 tosend = msg->sg.size;
416 if (psock->apply_bytes && psock->apply_bytes < tosend)
417 tosend = psock->apply_bytes;
[...]
443 sk_msg_return(sk, msg, tosend);
444 release_sock(sk);
446 origsize = msg->sg.size;
447 ret = tcp_bpf_sendmsg_redir(sk_redir, redir_ingress,
448 msg, tosend, flags);
449 sent = origsize - msg->sg.size;
[...]
454 lock_sock(sk);
455 if (unlikely(ret < 0)) {
456 int free = sk_msg_free_nocharge(sk, msg);
458 if (!cork)
459 *copied -= free;
460 }
[...]
487 if (eval == __SK_REDIRECT)
488 sk_mem_charge(sk, tosend - sent);
[...]
When running the selftest test_txmsg_redir_wait_sndmem with txmsg_apply,
the following warning will be reported:
------------[ cut here ]------------
WARNING: CPU: 6 PID: 57 at net/ipv4/af_inet.c:156 inet_sock_destruct+0x190/0x1a0
Modules linked in:
CPU: 6 UID: 0 PID: 57 Comm: kworker/6:0 Not tainted 6.12.0-rc1.bm.1-amd64+ #43
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
Workqueue: events sk_psock_destroy
RIP: 0010:inet_sock_destruct+0x190/0x1a0
RSP: 0018:ffffad0a8021fe08 EFLAGS: 00010206
RAX: 0000000000000011 RBX: ffff9aab4475b900 RCX: ffff9aab481a0800
RDX: 0000000000000303 RSI: 0000000000000011 RDI: ffff9aab4475b900
RBP: ffff9aab4475b990 R08: 0000000000000000 R09: ffff9aab40050ec0
R10: 0000000000000000 R11: ffff9aae6fdb1d01 R12: ffff9aab49c60400
R13: ffff9aab49c60598 R14: ffff9aab49c60598 R15: dead000000000100
FS: 0000000000000000(0000) GS:ffff9aae6fd80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffec7e47bd8 CR3: 00000001a1a1c004 CR4: 0000000000770ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
<TASK>
? __warn+0x89/0x130
? inet_sock_destruct+0x190/0x1a0
? report_bug+0xfc/0x1e0
? handle_bug+0x5c/0xa0
? exc_invalid_op+0x17/0x70
? asm_exc_invalid_op+0x1a/0x20
? inet_sock_destruct+0x190/0x1a0
__sk_destruct+0x25/0x220
sk_psock_destroy+0x2b2/0x310
process_scheduled_works+0xa3/0x3e0
worker_thread+0x117/0x240
? __pfx_worker_thread+0x10/0x10
kthread+0xcf/0x100
? __pfx_kthread+0x10/0x10
ret_from_fork+0x31/0x40
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
</TASK>
---[ end trace 0000000000000000 ]---
In __SK_REDIRECT, a more concise way is delaying the uncharging after sent
bytes are finalized, and uncharge this value. When (ret < 0), we shall
invoke sk_msg_free.
Same thing happens in case __SK_DROP, when tosend is set to apply_bytes,
we may miss uncharging (msg->sg.size - apply_bytes) bytes. The same
warning will be reported in selftest.
[...]
468 case __SK_DROP:
469 default:
470 sk_msg_free_partial(sk, msg, tosend);
471 sk_msg_apply_bytes(psock, tosend);
472 *copied -= (tosend + delta);
473 return -EACCES;
[...]
So instead of sk_msg_free_partial we can do sk_msg_free here.
The Linux kernel CVE team has assigned CVE-2024-56633 to this issue.
Affected and fixed versions
===========================
Issue introduced in 4.20 with commit 604326b41a6fb9b4a78b6179335decee0365cd8c and fixed in 5.4.287 with commit 905d82e6e77d16ec3e089c92b7b59a14899dfc1a
Issue introduced in 4.20 with commit 604326b41a6fb9b4a78b6179335decee0365cd8c and fixed in 5.10.231 with commit dbedc7e142df5ea238a46fdd7462c1c42cd36a10
Issue introduced in 4.20 with commit 604326b41a6fb9b4a78b6179335decee0365cd8c and fixed in 5.15.174 with commit 0d6cd1151e26fc7c2d5daa85e8984aaa685a1a12
Issue introduced in 4.20 with commit 604326b41a6fb9b4a78b6179335decee0365cd8c and fixed in 6.1.120 with commit 456f08d24afa51b5eb816c42e4ca1c44a247bd42
Issue introduced in 4.20 with commit 604326b41a6fb9b4a78b6179335decee0365cd8c and fixed in 6.6.66 with commit 206d56f41a1509cadd06e2178c26cb830e45057d
Issue introduced in 4.20 with commit 604326b41a6fb9b4a78b6179335decee0365cd8c and fixed in 6.12.5 with commit 5c9e3bb43a354a2245caebbbbb4a5b8c034fdd56
Issue introduced in 4.20 with commit 604326b41a6fb9b4a78b6179335decee0365cd8c and fixed in 6.13-rc2 with commit ca70b8baf2bd125b2a4d96e76db79375c07d7ff2
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-2024-56633
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/ipv4/tcp_bpf.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/905d82e6e77d16ec3e089c92b7b59a14899dfc1a
https://git.kernel.org/stable/c/dbedc7e142df5ea238a46fdd7462c1c42cd36a10
https://git.kernel.org/stable/c/0d6cd1151e26fc7c2d5daa85e8984aaa685a1a12
https://git.kernel.org/stable/c/456f08d24afa51b5eb816c42e4ca1c44a247bd42
https://git.kernel.org/stable/c/206d56f41a1509cadd06e2178c26cb830e45057d
https://git.kernel.org/stable/c/5c9e3bb43a354a2245caebbbbb4a5b8c034fdd56
https://git.kernel.org/stable/c/ca70b8baf2bd125b2a4d96e76db79375c07d7ff2
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