CVE-2024-41023

About vulnerability

In the Linux kernel, the following vulnerability has been resolved:

sched/deadline: Fix task_struct reference leak

During the execution of the following stress test with linux-rt:

stress-ng –cyclic 30 –timeout 30 –minimize –quiet

kmemleak frequently reported a memory leak concerning the task_struct:

unreferenced object 0xffff8881305b8000 (size 16136): comm “stress-ng”, pid 614, jiffies 4294883961 (age 286.412s) object hex dump (first 32 bytes): 02 40 00 00 00 00 00 00 00 00 00 00 00 00 00 00 .@………….. 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ……………. debug hex dump (first 16 bytes): 53 09 00 00 00 00 00 00 00 00 00 00 00 00 00 00 S…………… backtrace: [<00000000046b6790>] dup_task_struct+0x30/0x540 [<00000000c5ca0f0b>] copy_process+0x3d9/0x50e0 [<00000000ced59777>] kernel_clone+0xb0/0x770 [<00000000a50befdc>] __do_sys_clone+0xb6/0xf0 [<000000001dbf2008>] do_syscall_64+0x5d/0xf0 [<00000000552900ff>] entry_SYSCALL_64_after_hwframe+0x6e/0x76

The issue occurs in start_dl_timer(), which increments the task_struct reference count and sets a timer. The timer callback, dl_task_timer, is supposed to decrement the reference count upon expiration. However, if enqueue_task_dl() is called before the timer expires and cancels it, the reference count is not decremented, leading to the leak.

This patch fixes the reference leak by ensuring the task_struct reference count is properly decremented when the timer is canceled.

Affected product:

AlmaLinux 9.2 ESU , Amazon Linux 2 ELS , CentOS 6 ELS , CentOS 7 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , CloudLinux 6 ELS , CloudLinux 7 ELS , Oracle Linux 6 ELS , TuxCare 9.6 ESU

Affected packages:

kernel @ 5.14.0 (+10 more)

Live-patch status from KernelCare for each operating system.