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CVE-2024-42136

Updated on 30 Jul 2024

Severity

7.8 High severity

Details

CVSS score
7.8
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE ID
Links
NISTCIRCLRHELUbuntu

Overview

About vulnerability

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

cdrom: rearrange last_media_change check to avoid unintentional overflow

When running syzkaller with the newly reintroduced signed integer wrap sanitizer we encounter this splat:

[ 366.015950] UBSAN: signed-integer-overflow in ../drivers/cdrom/cdrom.c:2361:33 [ 366.021089] -9223372036854775808 - 346321 cannot be represented in type ‘__s64’ (aka ’long long’) [ 366.025894] program syz-executor.4 is using a deprecated SCSI ioctl, please convert it to SG_IO [ 366.027502] CPU: 5 PID: 28472 Comm: syz-executor.7 Not tainted 6.8.0-rc2-00035-gb3ef86b5a957 #1 [ 366.027512] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 366.027518] Call Trace: [ 366.027523] [ 366.027533] dump_stack_lvl+0x93/0xd0 [ 366.027899] handle_overflow+0x171/0x1b0 [ 366.038787] ata1.00: invalid multi_count 32 ignored [ 366.043924] cdrom_ioctl+0x2c3f/0x2d10 [ 366.063932] ? __pm_runtime_resume+0xe6/0x130 [ 366.071923] sr_block_ioctl+0x15d/0x1d0 [ 366.074624] ? __pfx_sr_block_ioctl+0x10/0x10 [ 366.077642] blkdev_ioctl+0x419/0x500 [ 366.080231] ? __pfx_blkdev_ioctl+0x10/0x10 …

Historically, the signed integer overflow sanitizer did not work in the kernel due to its interaction with -fwrapv but this has since been changed [1] in the newest version of Clang. It was re-enabled in the kernel with Commit 557f8c582a9ba8ab (“ubsan: Reintroduce signed overflow sanitizer”).

Let’s rearrange the check to not perform any arithmetic, thus not tripping the sanitizer.

Details

Affected product:
AlmaLinux 9.2 ESU , CentOS 6 ELS , CentOS 7 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , CloudLinux 6 ELS , CloudLinux 7 ELS , Oracle Linux 6 ELS , Oracle Linux 7 ELS , RHEL 7 ELS , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS
Affected packages:
kernel-uek @ 5.4.17 (+15 more)

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

cdrom: rearrange last_media_change check to avoid unintentional overflow

When running syzkaller with the newly reintroduced signed integer wrap sanitizer we encounter this splat:

[ 366.015950] UBSAN: signed-integer-overflow in ../drivers/cdrom/cdrom.c:2361:33 [ 366.021089] -9223372036854775808 - 346321 cannot be represented in type ‘__s64’ (aka ’long long’) [ 366.025894] program syz-executor.4 is using a deprecated SCSI ioctl, please convert it to SG_IO [ 366.027502] CPU: 5 PID: 28472 Comm: syz-executor.7 Not tainted 6.8.0-rc2-00035-gb3ef86b5a957 #1 [ 366.027512] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 366.027518] Call Trace: [ 366.027523] [ 366.027533] dump_stack_lvl+0x93/0xd0 [ 366.027899] handle_overflow+0x171/0x1b0 [ 366.038787] ata1.00: invalid multi_count 32 ignored [ 366.043924] cdrom_ioctl+0x2c3f/0x2d10 [ 366.063932] ? __pm_runtime_resume+0xe6/0x130 [ 366.071923] sr_block_ioctl+0x15d/0x1d0 [ 366.074624] ? __pfx_sr_block_ioctl+0x10/0x10 [ 366.077642] blkdev_ioctl+0x419/0x500 [ 366.080231] ? __pfx_blkdev_ioctl+0x10/0x10 …

Historically, the signed integer overflow sanitizer did not work in the kernel due to its interaction with -fwrapv but this has since been changed [1] in the newest version of Clang. It was re-enabled in the kernel with Commit 557f8c582a9ba8ab (“ubsan: Reintroduce signed overflow sanitizer”).

Let’s rearrange the check to not perform any arithmetic, thus not tripping the sanitizer.

Fixes