Subject: CVE-2024-42084: ftruncate: pass a signed offset

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

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

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

ftruncate: pass a signed offset

The old ftruncate() syscall, using the 32-bit off_t misses a sign
extension when called in compat mode on 64-bit architectures.  As a
result, passing a negative length accidentally succeeds in truncating
to file size between 2GiB and 4GiB.

Changing the type of the compat syscall to the signed compat_off_t
changes the behavior so it instead returns -EINVAL.

The native entry point, the truncate() syscall and the corresponding
loff_t based variants are all correct already and do not suffer
from this mistake.

The Linux kernel CVE team has assigned CVE-2024-42084 to this issue.

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

	Issue introduced in 3.9 with commit 3f6d078d4acc and fixed in 4.19.317 with commit c329760749b5
	Issue introduced in 3.9 with commit 3f6d078d4acc and fixed in 5.4.279 with commit f531d4bc6c55
	Issue introduced in 3.9 with commit 3f6d078d4acc and fixed in 5.10.221 with commit 84bf6b64a1a0
	Issue introduced in 3.9 with commit 3f6d078d4acc and fixed in 5.15.162 with commit dbb226d81cd0
	Issue introduced in 3.9 with commit 3f6d078d4acc and fixed in 6.1.97 with commit 5ae6af68410b
	Issue introduced in 3.9 with commit 3f6d078d4acc and fixed in 6.6.37 with commit 836359247b04
	Issue introduced in 3.9 with commit 3f6d078d4acc and fixed in 6.9.8 with commit 930a4c369f74
	Issue introduced in 3.9 with commit 3f6d078d4acc and fixed in 6.10 with commit 4b8e88e563b5

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-2024-42084
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:
	fs/open.c
	include/linux/compat.h
	include/linux/syscalls.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/c329760749b5419769e57cb2be80955d2805f9c9
	https://git.kernel.org/stable/c/f531d4bc6c5588d713359e42ed65e46816d841d8
	https://git.kernel.org/stable/c/84bf6b64a1a0dfc6de7e1b1c776d58d608e7865a
	https://git.kernel.org/stable/c/dbb226d81cd02cee140139c2369791e6f61f2007
	https://git.kernel.org/stable/c/5ae6af68410bdad6181ec82104bb9985a7a6a0fa
	https://git.kernel.org/stable/c/836359247b0403e0634bfbc83e5bb8063fad287a
	https://git.kernel.org/stable/c/930a4c369f74da26816eaaa71b5888d29b759c27
	https://git.kernel.org/stable/c/4b8e88e563b5f666446d002ad0dc1e6e8e7102b0