Subject: CVE-2024-46783: tcp_bpf: fix return value of tcp_bpf_sendmsg()

From: Greg Kroah-Hartman <[email-masked]>

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

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

tcp_bpf: fix return value of tcp_bpf_sendmsg()

When we cork messages in psock->cork, the last message triggers the
flushing will result in sending a sk_msg larger than the current
message size. In this case, in tcp_bpf_send_verdict(), 'copied' becomes
negative at least in the following case:

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); // <==== HERE
473                 return -EACCES;

Therefore, it could lead to the following BUG with a proper value of
'copied' (thanks to syzbot). We should not use negative 'copied' as a
return value here.

  ------------[ cut here ]------------
  kernel BUG at net/socket.c:733!
  Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
  Modules linked in:
  CPU: 0 UID: 0 PID: 3265 Comm: syz-executor510 Not tainted 6.11.0-rc3-syzkaller-00060-gd07b43284ab3 #0
  Hardware name: linux,dummy-virt (DT)
  pstate: 61400009 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
  pc : sock_sendmsg_nosec net/socket.c:733 [inline]
  pc : sock_sendmsg_nosec net/socket.c:728 [inline]
  pc : __sock_sendmsg+0x5c/0x60 net/socket.c:745
  lr : sock_sendmsg_nosec net/socket.c:730 [inline]
  lr : __sock_sendmsg+0x54/0x60 net/socket.c:745
  sp : ffff800088ea3b30
  x29: ffff800088ea3b30 x28: fbf00000062bc900 x27: 0000000000000000
  x26: ffff800088ea3bc0 x25: ffff800088ea3bc0 x24: 0000000000000000
  x23: f9f00000048dc000 x22: 0000000000000000 x21: ffff800088ea3d90
  x20: f9f00000048dc000 x19: ffff800088ea3d90 x18: 0000000000000001
  x17: 0000000000000000 x16: 0000000000000000 x15: 000000002002ffaf
  x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
  x11: 0000000000000000 x10: ffff8000815849c0 x9 : ffff8000815b49c0
  x8 : 0000000000000000 x7 : 000000000000003f x6 : 0000000000000000
  x5 : 00000000000007e0 x4 : fff07ffffd239000 x3 : fbf00000062bc900
  x2 : 0000000000000000 x1 : 0000000000000000 x0 : 00000000fffffdef
  Call trace:
   sock_sendmsg_nosec net/socket.c:733 [inline]
   __sock_sendmsg+0x5c/0x60 net/socket.c:745
   ____sys_sendmsg+0x274/0x2ac net/socket.c:2597
   ___sys_sendmsg+0xac/0x100 net/socket.c:2651
   __sys_sendmsg+0x84/0xe0 net/socket.c:2680
   __do_sys_sendmsg net/socket.c:2689 [inline]
   __se_sys_sendmsg net/socket.c:2687 [inline]
   __arm64_sys_sendmsg+0x24/0x30 net/socket.c:2687
   __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
   invoke_syscall+0x48/0x110 arch/arm64/kernel/syscall.c:49
   el0_svc_common.constprop.0+0x40/0xe0 arch/arm64/kernel/syscall.c:132
   do_el0_svc+0x1c/0x28 arch/arm64/kernel/syscall.c:151
   el0_svc+0x34/0xec arch/arm64/kernel/entry-common.c:712
   el0t_64_sync_handler+0x100/0x12c arch/arm64/kernel/entry-common.c:730
   el0t_64_sync+0x19c/0x1a0 arch/arm64/kernel/entry.S:598
  Code: f9404463 d63f0060 3108441f 54fffe81 (d4210000)
  ---[ end trace 0000000000000000 ]---

The Linux kernel CVE team has assigned CVE-2024-46783 to this issue.

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

	Issue introduced in 4.17 with commit 4f738adba30a and fixed in 5.4.284 with commit 6f9fdf5806cc
	Issue introduced in 4.17 with commit 4f738adba30a and fixed in 5.10.226 with commit 3efe53eb221a
	Issue introduced in 4.17 with commit 4f738adba30a and fixed in 5.15.167 with commit 78bb38d9c5a3
	Issue introduced in 4.17 with commit 4f738adba30a and fixed in 6.1.110 with commit 810a4e7d92de
	Issue introduced in 4.17 with commit 4f738adba30a and fixed in 6.6.51 with commit c8219a27fa43
	Issue introduced in 4.17 with commit 4f738adba30a and fixed in 6.10.10 with commit 126d72b726c4
	Issue introduced in 4.17 with commit 4f738adba30a and fixed in 6.11 with commit fe1910f9337b

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-2024-46783
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/6f9fdf5806cced888c43512bccbdf7fefd50f510
	https://git.kernel.org/stable/c/3efe53eb221a38e207c1e3f81c51e4ca057d50c2
	https://git.kernel.org/stable/c/78bb38d9c5a311c5f8bdef7c9557d7d81ca30e4a
	https://git.kernel.org/stable/c/810a4e7d92dea4074cb04c25758320909d752193
	https://git.kernel.org/stable/c/c8219a27fa43a2cbf99f5176f6dddfe73e7a24ae
	https://git.kernel.org/stable/c/126d72b726c4cf1119f3a7fe413a78d341c3fea9
	https://git.kernel.org/stable/c/fe1910f9337bd46a9343967b547ccab26b4b2c6e