CVE-2024-35979

Published May 20, 2024

Last updated a year ago

Overview

Description
In the Linux kernel, the following vulnerability has been resolved: raid1: fix use-after-free for original bio in raid1_write_request() r1_bio->bios[] is used to record new bios that will be issued to underlying disks, however, in raid1_write_request(), r1_bio->bios[] will set to the original bio temporarily. Meanwhile, if blocked rdev is set, free_r1bio() will be called causing that all r1_bio->bios[] to be freed: raid1_write_request() r1_bio = alloc_r1bio(mddev, bio); -> r1_bio->bios[] is NULL for (i = 0; i < disks; i++) -> for each rdev in conf // first rdev is normal r1_bio->bios[0] = bio; -> set to original bio // second rdev is blocked if (test_bit(Blocked, &rdev->flags)) break if (blocked_rdev) free_r1bio() put_all_bios() bio_put(r1_bio->bios[0]) -> original bio is freed Test scripts: mdadm -CR /dev/md0 -l1 -n4 /dev/sd[abcd] --assume-clean fio -filename=/dev/md0 -ioengine=libaio -rw=write -bs=4k -numjobs=1 \ -iodepth=128 -name=test -direct=1 echo blocked > /sys/block/md0/md/rd2/state Test result: BUG bio-264 (Not tainted): Object already free ----------------------------------------------------------------------------- Allocated in mempool_alloc_slab+0x24/0x50 age=1 cpu=1 pid=869 kmem_cache_alloc+0x324/0x480 mempool_alloc_slab+0x24/0x50 mempool_alloc+0x6e/0x220 bio_alloc_bioset+0x1af/0x4d0 blkdev_direct_IO+0x164/0x8a0 blkdev_write_iter+0x309/0x440 aio_write+0x139/0x2f0 io_submit_one+0x5ca/0xb70 __do_sys_io_submit+0x86/0x270 __x64_sys_io_submit+0x22/0x30 do_syscall_64+0xb1/0x210 entry_SYSCALL_64_after_hwframe+0x6c/0x74 Freed in mempool_free_slab+0x1f/0x30 age=1 cpu=1 pid=869 kmem_cache_free+0x28c/0x550 mempool_free_slab+0x1f/0x30 mempool_free+0x40/0x100 bio_free+0x59/0x80 bio_put+0xf0/0x220 free_r1bio+0x74/0xb0 raid1_make_request+0xadf/0x1150 md_handle_request+0xc7/0x3b0 md_submit_bio+0x76/0x130 __submit_bio+0xd8/0x1d0 submit_bio_noacct_nocheck+0x1eb/0x5c0 submit_bio_noacct+0x169/0xd40 submit_bio+0xee/0x1d0 blkdev_direct_IO+0x322/0x8a0 blkdev_write_iter+0x309/0x440 aio_write+0x139/0x2f0 Since that bios for underlying disks are not allocated yet, fix this problem by using mempool_free() directly to free the r1_bio.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Analyzed
Products
linux_kernel

Risk scores

CVSS 3.1

Type
Primary
Base score
7.8
Impact score
5.9
Exploitability score
1.8
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Severity
HIGH

Weaknesses

nvd@nist.gov
CWE-416

Social media

Hype score
Not currently trending

Configurations

  1. In the Linux kernel, the following vulnerability has been resolved: coresight: tmc-etr: Fix race condition between sysfs and perf mode When trying to run perf and sysfs mode simultaneously, the WARN_ON() in tmc_etr_enable_hw() is triggered sometimes: WARNING: CPU: 42 PID: 3911571 at drivers/hwtracing/coresight/coresight-tmc-etr.c:1060 tmc_etr_enable_hw+0xc0/0xd8 [coresight_tmc] [..snip..] Call trace: tmc_etr_enable_hw+0xc0/0xd8 [coresight_tmc] (P) tmc_enable_etr_sink+0x11c/0x250 [coresight_tmc] (L) tmc_enable_etr_sink+0x11c/0x250 [coresight_tmc] coresight_enable_path+0x1c8/0x218 [coresight] coresight_enable_sysfs+0xa4/0x228 [coresight] enable_source_store+0x58/0xa8 [coresight] dev_attr_store+0x20/0x40 sysfs_kf_write+0x4c/0x68 kernfs_fop_write_iter+0x120/0x1b8 vfs_write+0x2c8/0x388 ksys_write+0x74/0x108 __arm64_sys_write+0x24/0x38 el0_svc_common.constprop.0+0x64/0x148 do_el0_svc+0x24/0x38 el0_svc+0x3c/0x130 el0t_64_sync_handler+0xc8/0xd0 el0t_64_sync+0x1ac/0x1b0 ---[ end trace 0000000000000000 ]--- Since the enablement of sysfs mode is separeted into two critical regions, one for sysfs buffer allocation and another for hardware enablement, it's possible to race with the perf mode. Fix this by double check whether the perf mode's been used before enabling the hardware in sysfs mode. mode: [sysfs mode] [perf mode] tmc_etr_get_sysfs_buffer() spin_lock(&drvdata->spinlock) [sysfs buffer allocation] spin_unlock(&drvdata->spinlock) spin_lock(&drvdata->spinlock) tmc_etr_enable_hw() drvdata->etr_buf = etr_perf->etr_buf spin_unlock(&drvdata->spinlock) spin_lock(&drvdata->spinlock) tmc_etr_enable_hw() WARN_ON(drvdata->etr_buf) // WARN sicne etr_buf initialized at the perf side spin_unlock(&drvdata->spinlock) With this fix, we retain the check for CS_MODE_PERF in get_etr_sysfs_buf. This ensures we verify whether the perf mode's already running before we actually allocate the buffer. Then we can save the time of allocating/freeing the sysfs buffer if race with the perf mode.CVE-2026-46272