CyberSecBulletin
CVE-2024-26724NVD status: Analyzed

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2024-26724 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 1596126ea50228f0ed96697bae4e9368fda02c56, aa1eec2f546f2afa8c98ec41e5d8ee488165d685 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.23% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 1596126ea50228f0ed96697bae4e9368fda02c56 or aa1eec2f546f2afa8c98ec41e5d8ee488165d685, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.7.6 or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux496fd0a26bbf73b6b12407ee4fbe5ff49d659a6d up to, but not including, 1596126ea50228f0ed96697bae4e9368fda02c56; 496fd0a26bbf73b6b12407ee4fbe5ff49d659a6d up to, but not including, aa1eec2f546f2afa8c98ec41e5d8ee488165d685; 6.71596126ea50228f0ed96697bae4e9368fda02c56, aa1eec2f546f2afa8c98ec41e5d8ee488165d685
LinuxLinux Kernel6.7 up to, but not including, 6.7.6; 6.86.7.6

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Official description

In the Linux kernel, the following vulnerability has been resolved: net/mlx5: DPLL, Fix possible use after free after delayed work timer triggers I managed to hit following use after free warning recently: [ 2169.711665] ================================================================== [ 2169.714009] BUG: KASAN: slab-use-after-free in __run_timers.part.0+0x179/0x4c0 [ 2169.716293] Write of size 8 at addr ffff88812b326a70 by task swapper/4/0 [ 2169.719022] CPU: 4 PID: 0 Comm: swapper/4 Not tainted 6.8.0-rc2jiri+ #2 [ 2169.720974] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 [ 2169.722457] Call Trace: [ 2169.722756] <IRQ> [ 2169.723024] dump_stack_lvl+0x58/0xb0 [ 2169.723417] print_report+0xc5/0x630 [ 2169.723807] ? __virt_addr_valid+0x126/0x2b0 [ 2169.724268] kasan_report+0xbe/0xf0 [ 2169.724667] ? __run_timers.part.0+0x179/0x4c0 [ 2169.725116] ? __run_timers.part.0+0x179/0x4c0 [ 2169.725570] __run_timers.part.0+0x179/0x4c0 [ 2169.726003] ? call_timer_fn+0x320/0x320 [ 2169.726404] ? lock_downgrade+0x3a0/0x3a0 [ 2169.726820] ? kvm_clock_get_cycles+0x14/0x20 [ 2169.727257] ? ktime_get+0x92/0x150 [ 2169.727630] ? lapic_next_deadline+0x35/0x60 [ 2169.728069] run_timer_softirq+0x40/0x80 [ 2169.728475] __do_softirq+0x1a1/0x509 [ 2169.728866] irq_exit_rcu+0x95/0xc0 [ 2169.729241] sysvec_apic_timer_interrupt+0x6b/0x80 [ 2169.729718] </IRQ> [ 2169.729993] <TASK> [ 2169.730259] asm_sysvec_apic_timer_interrupt+0x16/0x20 [ 2169.730755] RIP: 0010:default_idle+0x13/0x20 [ 2169.731190] Code: c0 08 00 00 00 4d 29 c8 4c 01 c7 4c 29 c2 e9 72 ff ff ff cc cc cc cc 8b 05 9a 7f 1f 02 85 c0 7e 07 0f 00 2d cf 69 43 00 fb f4 <fa> c3 66 66 2e 0f 1f 84 00 00 00 00 00 65 48 8b 04 25 c0 93 04 00 [ 2169.732759] RSP: 0018:ffff888100dbfe10 EFLAGS: 00000242 [ 2169.733264] RAX: 0000000000000001 RBX: ffff888100d9c200 RCX: ffffffff8241bd62 [ 2169.733925] RDX: ffffed109a848b15 RSI: 0000000000000004 RDI: ffffffff8127ac55 [ 2169.734566] RBP: 0000000000000004 R08: 0000000000000000 R09: ffffed109a848b14 [ 2169.735200] R10: ffff8884d42458a3 R11: 000000000000ba7e R12: ffffffff83d7d3a0 [ 2169.735835] R13: 1ffff110201b7fc6 R14: 0000000000000000 R15: ffff888100d9c200 [ 2169.736478] ? ct_kernel_exit.constprop.0+0xa2/0xc0 [ 2169.736954] ? do_idle+0x285/0x290 [ 2169.737323] default_idle_call+0x63/0x90 [ 2169.737730] do_idle+0x285/0x290 [ 2169.738089] ? arch_cpu_idle_exit+0x30/0x30 [ 2169.738511] ? mark_held_locks+0x1a/0x80 [ 2169.738917] ? lockdep_hardirqs_on_prepare+0x12e/0x200 [ 2169.739417] cpu_startup_entry+0x30/0x40 [ 2169.739825] start_secondary+0x19a/0x1c0 [ 2169.740229] ? set_cpu_sibling_map+0xbd0/0xbd0 [ 2169.740673] secondary_startup_64_no_verify+0x15d/0x16b [ 2169.741179] </TASK> [ 2169.741686] Allocated by task 1098: [ 2169.742058] kasan_save_stack+0x1c/0x40 [ 2169.742456] kasan_save_track+0x10/0x30 [ 2169.742852] __kasan_kmalloc+0x83/0x90 [ 2169.743246] mlx5_dpll_probe+0xf5/0x3c0 [mlx5_dpll] [ 2169.743730] auxiliary_bus_probe+0x62/0xb0 [ 2169.744148] really_probe+0x127/0x590 [ 2169.744534] __driver_probe_device+0xd2/0x200 [ 2169.744973] device_driver_attach+0x6b/0xf0 [ 2169.745402] bind_store+0x90/0xe0 [ 2169.745761] kernfs_fop_write_iter+0x1df/0x2a0 [ 2169.746210] vfs_write+0x41f/0x790 [ 2169.746579] ksys_write+0xc7/0x160 [ 2169.746947] do_syscall_64+0x6f/0x140 [ 2169.747333] entry_SYSCALL_64_after_hwframe+0x46/0x4e [ 2169.748049] Freed by task 1220: [ 2169.748393] kasan_save_stack+0x1c/0x40 [ 2169.748789] kasan_save_track+0x10/0x30 [ 2169.749188] kasan_save_free_info+0x3b/0x50 [ 2169.749621] poison_slab_object+0x106/0x180 [ 2169.750044] __kasan_slab_free+0x14/0x50 [ 2169.750451] kfree+0x118/0x330 [ 2169.750792] mlx5_dpll_remove+0xf5/0x110 [mlx5_dpll] [ 2169.751271] auxiliary_bus_remove+0x2e/0x40 [ 2169.751694] device_release_driver_internal+0x24b/0x2e0 [ 2169.752191] unbind_store+0xa6/0xb0 [ 2169.752563] kernfs_fo ---truncated---

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.

More Use After Free vulnerabilities (CWE-416)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Use After Free vulnerabilities

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