Rocky Linux: CVE-2024-39501: kernel-rt (RLSA-2024-7001)

Rocky Linux: CVE-2024-39501: kernel-rt (RLSA-2024-7001)

Severity

4

CVSS

(AV:L/AC:M/Au:N/C:P/I:P/A:P)

Published

07/12/2024

Created

10/03/2024

Added

10/02/2024

Modified

11/18/2024

Description

In the Linux kernel, the following vulnerability has been resolved: drivers: core: synchronize really_probe() and dev_uevent() Synchronize the dev->driver usage in really_probe() and dev_uevent(). These can run in different threads, what can result in the following race condition for dev->driver uninitialization: Thread #1: ========== really_probe() { ... probe_failed: ... device_unbind_cleanup(dev) { ... dev->driver = NULL; // <= Failed probe sets dev->driver to NULL ... } ... } Thread #2: ========== dev_uevent() { ... if (dev->driver) // If dev->driver is NULLed from really_probe() from here on, // after above check, the system crashes add_uevent_var(env, "DRIVER=%s", dev->driver->name); ... } really_probe() holds the lock, already. So nothing needs to be done there. dev_uevent() is called with lock held, often, too. But not always. What implies that we can't add any locking in dev_uevent() itself. So fix this race by adding the lock to the non-protected path. This is the path where above race is observed: dev_uevent+0x235/0x380 uevent_show+0x10c/0x1f0<= Add lock here dev_attr_show+0x3a/0xa0 sysfs_kf_seq_show+0x17c/0x250 kernfs_seq_show+0x7c/0x90 seq_read_iter+0x2d7/0x940 kernfs_fop_read_iter+0xc6/0x310 vfs_read+0x5bc/0x6b0 ksys_read+0xeb/0x1b0 __x64_sys_read+0x42/0x50 x64_sys_call+0x27ad/0x2d30 do_syscall_64+0xcd/0x1d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f Similar cases are reported by syzkaller in https://syzkaller.appspot.com/bug?extid=ffa8143439596313a85a But these are regarding the *initialization* of dev->driver dev->driver = drv; As this switches dev->driver to non-NULL these reports can be considered to be false-positives (which should be "fixed" by this commit, as well, though). The same issue was reported and tried to be fixed back in 2015 in https://lore.kernel.org/lkml/[email protected]/ already.

Solution(s)

• rocky-upgrade-kernel-rt
• rocky-upgrade-kernel-rt-core
• rocky-upgrade-kernel-rt-debug
• rocky-upgrade-kernel-rt-debug-core
• rocky-upgrade-kernel-rt-debug-debuginfo
• rocky-upgrade-kernel-rt-debug-devel
• rocky-upgrade-kernel-rt-debug-kvm
• rocky-upgrade-kernel-rt-debug-modules
• rocky-upgrade-kernel-rt-debug-modules-extra
• rocky-upgrade-kernel-rt-debuginfo
• rocky-upgrade-kernel-rt-debuginfo-common-x86_64
• rocky-upgrade-kernel-rt-devel
• rocky-upgrade-kernel-rt-kvm
• rocky-upgrade-kernel-rt-modules
• rocky-upgrade-kernel-rt-modules-extra

References

• https://attackerkb.com/topics/cve-2024-39501
• CVE - 2024-39501
• https://errata.rockylinux.org/RLSA-2024:7001