CVE-2024-26640: tcp: add sanity checks to rx zerocopy

CVE-2024-26640: tcp: add sanity checks to rx zerocopy

[Lee Jones]

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

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

tcp: add sanity checks to rx zerocopy

TCP rx zerocopy intent is to map pages initially allocated
from NIC drivers, not pages owned by a fs.

This patch adds to can_map_frag() these additional checks:

- Page must not be a compound one.
- page->mapping must be NULL.

This fixes the panic reported by ZhangPeng.

syzbot was able to loopback packets built with sendfile(),
mapping pages owned by an ext4 file to TCP rx zerocopy.

r3 = socket$inet_tcp(0x2, 0x1, 0x0)
mmap(&(0x7f0000ff9000/0x4000)=nil, 0x4000, 0x0, 0x12, r3, 0x0)
r4 = socket$inet_tcp(0x2, 0x1, 0x0)
bind$inet(r4, &(0x7f0000000000)={0x2, 0x4e24, @multicast1}, 0x10)
connect$inet(r4, &(0x7f00000006c0)={0x2, 0x4e24, @empty}, 0x10)
r5 = openat$dir(0xffffffffffffff9c, &(0x7f00000000c0)='./file0\x00',
    0x181e42, 0x0)
fallocate(r5, 0x0, 0x0, 0x85b8)
sendfile(r4, r5, 0x0, 0x8ba0)
getsockopt$inet_tcp_TCP_ZEROCOPY_RECEIVE(r4, 0x6, 0x23,
    &(0x7f00000001c0)={&(0x7f0000ffb000/0x3000)=nil, 0x3000, 0x0, 0x0, 0x0,
    0x0, 0x0, 0x0, 0x0}, &(0x7f0000000440)=0x40)
r6 = openat$dir(0xffffffffffffff9c, &(0x7f00000000c0)='./file0\x00',
    0x181e42, 0x0)

The Linux kernel CVE team has assigned CVE-2024-26640 to this issue.


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

	Issue introduced in 4.18 with commit 93ab6cc69162 and fixed in 5.10.210 with commit f48bf9a83b16
	Issue introduced in 4.18 with commit 93ab6cc69162 and fixed in 5.15.149 with commit 718f446e6031
	Issue introduced in 4.18 with commit 93ab6cc69162 and fixed in 6.1.77 with commit b383d4ea272f
	Issue introduced in 4.18 with commit 93ab6cc69162 and fixed in 6.6.16 with commit d15cc0f66884
	Issue introduced in 4.18 with commit 93ab6cc69162 and fixed in 6.7.4 with commit 1b8adcc0e2c5
	Issue introduced in 4.18 with commit 93ab6cc69162 and fixed in 6.8 with commit 577e4432f3ac

Please see https://www.kernel.org or 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-2024-26640
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.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/f48bf9a83b1666d934247cb58a9887d7b3127b6f
	https://git.kernel.org/stable/c/718f446e60316bf606946f7f42367d691d21541e
	https://git.kernel.org/stable/c/b383d4ea272fe5795877506dcce5aad1f6330e5e
	https://git.kernel.org/stable/c/d15cc0f66884ef2bed28c7ccbb11c102aa3a0760
	https://git.kernel.org/stable/c/1b8adcc0e2c584fec778add7777fe28e20781e60
	https://git.kernel.org/stable/c/577e4432f3ac810049cb7e6b71f4d96ec7c6e894