cbcvebase.
CVE-2024-56693
published 2024-12-28

CVE-2024-56693: In the Linux kernel, the following vulnerability has been resolved: brd: defer automatic disk creation until module initialization succeeds My colleague Wupeng…

PriorityP337high7.8CVSS 3.1
AVLACLPRLUINSUCHIHAH
EPSS
0.24%
15.7th percentile
In the Linux kernel, the following vulnerability has been resolved: brd: defer automatic disk creation until module initialization succeeds My colleague Wupeng found the following problems during fault injection: BUG: unable to handle page fault for address: fffffbfff809d073 PGD 6e648067 P4D 123ec8067 PUD 123ec4067 PMD 100e38067 PTE 0 Oops: Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI CPU: 5 UID: 0 PID: 755 Comm: modprobe Not tainted 6.12.0-rc3+ #17 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 RIP: 0010:__asan_load8+0x4c/0xa0 ... Call Trace: blkdev_put_whole+0x41/0x70 bdev_release+0x1a3/0x250 blkdev_release+0x11/0x20 __fput+0x1d7/0x4a0 task_work_run+0xfc/0x180 syscall_exit_to_user_mode+0x1de/0x1f0 do_syscall_64+0x6b/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e loop_init() is calling loop_add() after __register_blkdev() succeeds and is ignoring disk_add() failure from loop_add(), for loop_add() failure is not fatal and successfully created disks are already visible to bdev_open(). brd_init() is currently calling brd_alloc() before __register_blkdev() succeeds and is releasing successfully created disks when brd_init() returns an error. This can cause UAF for the latter two case: case 1: T1: modprobe brd brd_init brd_alloc(0) // success add_disk disk_scan_partitions bdev_file_open_by_dev // alloc file fput // won't free until back to userspace brd_alloc(1) // failed since mem alloc error inject // error path for modprobe will release code segment // back to userspace __fput blkdev_release bdev_release blkdev_put_whole bdev->bd_disk->fops->release // fops is freed now, UAF! case 2: T1: T2: modprobe brd brd_init brd_alloc(0) // success open(/dev/ram0) brd_alloc(1) // fail // error path for modprobe close(/dev/ram0) ... /* UAF! */ bdev->bd_disk->fops->release Fix this problem by following what loop_init() does. Besides, reintroduce brd_devices_mutex to help serialize modifications to brd_list.

Affected

20 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.1.123-1 (bookworm)linux 6.1.123-1 (bookworm)
debianlinux-6.1< linux 6.1.123-1 (bookworm)linux 6.1.123-1 (bookworm)
linuxlinux
linuxlinux>= 7f9b348cb5e94259acdcbafbcaed55d3bb515304 < 41219c147df8bbd6591f59af5d695fb6c9a1cbff41219c147df8bbd6591f59af5d695fb6c9a1cbff
linuxlinux>= 7f9b348cb5e94259acdcbafbcaed55d3bb515304 < 259bf925583ec9e3781df778cadf00594095090d259bf925583ec9e3781df778cadf00594095090d
linuxlinux>= 7f9b348cb5e94259acdcbafbcaed55d3bb515304 < 410896624db639500f24f46478b4bfa05c76bf56410896624db639500f24f46478b4bfa05c76bf56
linuxlinux>= 7f9b348cb5e94259acdcbafbcaed55d3bb515304 < c0c2744cd2939ec5999c51dbaf2af16886548b7bc0c2744cd2939ec5999c51dbaf2af16886548b7b
linuxlinux>= 7f9b348cb5e94259acdcbafbcaed55d3bb515304 < 63dfd728b30f79495dacc886127695a37980515263dfd728b30f79495dacc886127695a379805152
linuxlinux>= 7f9b348cb5e94259acdcbafbcaed55d3bb515304 < 826cc42adf44930a633d11a5993676d85ddb0842826cc42adf44930a633d11a5993676d85ddb0842
linuxlinux_kernel>= 0 < 6.1.123-16.1.123-1
linuxlinux_kernel>= 0 < 6.12.3-16.12.3-1
linuxlinux_kernel>= 0 < 6.12.3-16.12.3-1
linuxlinux_kernel>= 0 < 5.15.0-135.1465.15.0-135.146
linuxlinux_kernel>= 0 < 6.8.0-58.606.8.0-58.60
linuxlinux_kernel>= 0 < 6.11.0-18.186.11.0-18.18
linuxlinux_kernel>= 5.14 < 5.15.1745.15.174
linuxlinux_kernel>= 5.16 < 6.1.1206.1.120
linuxlinux_kernel>= 6.12 < 6.12.26.12.2
linuxlinux_kernel>= 6.2 < 6.6.646.6.64
linuxlinux_kernel>= 6.7 < 6.11.116.11.11

CVSS provenance

nvdv3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
osv8.8HIGH
vendor_ubuntu8.8HIGH
vendor_debian7.8HIGH
vendor_redhat7.8HIGH
Stop checking back — get the weekly exploitation signal.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.