CVE-2024-26935

CVE Details

Release Date:

2024-05-01

Description

In the Linux kernel, the following vulnerability has been resolved:\nscsi: core: Fix unremoved procfs host directory regression\nCommit fc663711b944 ('scsi: core: Remove the /proc/scsi/\ndirectory earlier') fixed a bug related to modules loading/unloading, by\nadding a call to scsi_proc_hostdir_rm() on scsi_remove_host(). But that led\nto a potential duplicate call to the hostdir_rm() routine, since it's also\ncalled from scsi_host_dev_release(). That triggered a regression report,\nwhich was then fixed by commit be03df3d4bfe ('scsi: core: Fix a procfs host\ndirectory removal regression'). The fix just dropped the hostdir_rm() call\nfrom dev_release().\nBut it happens that this proc directory is created on scsi_host_alloc(),\nand that function 'pairs' with scsi_host_dev_release(), while\nscsi_remove_host() pairs with scsi_add_host(). In other words, it seems the\nreason for removing the proc directory on dev_release() was meant to cover\ncases in which a SCSI host structure was allocated, but the call to\nscsi_add_host() didn't happen. And that pattern happens to exist in some\nerror paths, for example.\nSyzkaller causes that by using USB raw gadget device, error'ing on\nusb-storage driver, at usb_stor_probe2(). By checking that path, we can see\nthat the BadDevice label leads to a scsi_host_put() after a SCSI host\nallocation, but there's no call to scsi_add_host() in such path. That leads\nto messages like this in dmesg (and a leak of the SCSI host proc\nstructure):\nusb-storage 4-1:87.51: USB Mass Storage device detected\nproc_dir_entry 'scsi/usb-storage' already registered\nWARNING: CPU: 1 PID: 3519 at fs/proc/generic.c:377 proc_register+0x347/0x4e0 fs/proc/generic.c:376\nThe proper fix seems to still call scsi_proc_hostdir_rm() on dev_release(),\nbut guard that with the state check for SHOST_CREATED; there is even a\ncomment in scsi_host_dev_release() detailing that: such conditional is\nmeant for cases where the SCSI host was allocated but there was no calls to\n{add,remove}_host(), like the usb-storage case.\nThis is what we propose here and with that, the error path of usb-storage\ndoes not trigger the warning anymore.

See more information about CVE-2024-26935 from MITRE CVE dictionary and NIST NVD

CVSS Scoring

NOTE: The following CVSS v3.1 metrics and score provided are preliminary and subject to review.

Base Score:	5.5	CVSS Vector:	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector:	Local network	Attack Complexity:	Low
Privileges Required:	Low	User Interaction:	None
Scope:	Unchanged	Confidentiality Impact:	None
Integrity Impact:	None	Availability Impact:	High

Errata information

Platform	Errata	Release Date
Oracle Linux version 9 (kernel)	ELSA-2024-8617	2024-10-30