CVE-2024-39501

NameCVE-2024-39501
DescriptionIn 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/1421259054-2574-1-git-send-email-a.sangwan@samsung.com/ already.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDSA-5730-1, DSA-5731-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)jessie, jessie (lts)3.16.84-1vulnerable
stretch (security)4.9.320-2vulnerable
stretch (lts), stretch4.9.320-3vulnerable
buster (security), buster, buster (lts)4.19.316-1vulnerable
bullseye5.10.223-1fixed
bullseye (security)5.10.226-1fixed
bookworm6.1.115-1fixed
bookworm (security)6.1.112-1fixed
trixie6.11.7-1fixed
sid6.11.9-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcejessie(unfixed)end-of-life
linuxsourcestretch(unfixed)end-of-life
linuxsourcebuster(unfixed)end-of-life
linuxsourcebullseye5.10.221-1DSA-5730-1
linuxsourcebookworm6.1.99-1DSA-5731-1
linuxsource(unstable)6.9.7-1

Notes

https://git.kernel.org/linus/c0a40097f0bc81deafc15f9195d1fb54595cd6d0 (6.10-rc4)

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