CVE-2024-26987

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> mm/memory-failure: fix deadlock when hugetlb_optimize_vmemmap is enabled<br /> <br /> When I did hard offline test with hugetlb pages, below deadlock occurs:<br /> <br /> ======================================================<br /> WARNING: possible circular locking dependency detected<br /> 6.8.0-11409-gf6cef5f8c37f #1 Not tainted<br /> ------------------------------------------------------<br /> bash/46904 is trying to acquire lock:<br /> ffffffffabe68910 (cpu_hotplug_lock){++++}-{0:0}, at: static_key_slow_dec+0x16/0x60<br /> <br /> but task is already holding lock:<br /> ffffffffabf92ea8 (pcp_batch_high_lock){+.+.}-{3:3}, at: zone_pcp_disable+0x16/0x40<br /> <br /> which lock already depends on the new lock.<br /> <br /> the existing dependency chain (in reverse order) is:<br /> <br /> -&gt; #1 (pcp_batch_high_lock){+.+.}-{3:3}:<br /> __mutex_lock+0x6c/0x770<br /> page_alloc_cpu_online+0x3c/0x70<br /> cpuhp_invoke_callback+0x397/0x5f0<br /> __cpuhp_invoke_callback_range+0x71/0xe0<br /> _cpu_up+0xeb/0x210<br /> cpu_up+0x91/0xe0<br /> cpuhp_bringup_mask+0x49/0xb0<br /> bringup_nonboot_cpus+0xb7/0xe0<br /> smp_init+0x25/0xa0<br /> kernel_init_freeable+0x15f/0x3e0<br /> kernel_init+0x15/0x1b0<br /> ret_from_fork+0x2f/0x50<br /> ret_from_fork_asm+0x1a/0x30<br /> <br /> -&gt; #0 (cpu_hotplug_lock){++++}-{0:0}:<br /> __lock_acquire+0x1298/0x1cd0<br /> lock_acquire+0xc0/0x2b0<br /> cpus_read_lock+0x2a/0xc0<br /> static_key_slow_dec+0x16/0x60<br /> __hugetlb_vmemmap_restore_folio+0x1b9/0x200<br /> dissolve_free_huge_page+0x211/0x260<br /> __page_handle_poison+0x45/0xc0<br /> memory_failure+0x65e/0xc70<br /> hard_offline_page_store+0x55/0xa0<br /> kernfs_fop_write_iter+0x12c/0x1d0<br /> vfs_write+0x387/0x550<br /> ksys_write+0x64/0xe0<br /> do_syscall_64+0xca/0x1e0<br /> entry_SYSCALL_64_after_hwframe+0x6d/0x75<br /> <br /> other info that might help us debug this:<br /> <br /> Possible unsafe locking scenario:<br /> <br /> CPU0 CPU1<br /> ---- ----<br /> lock(pcp_batch_high_lock);<br /> lock(cpu_hotplug_lock);<br /> lock(pcp_batch_high_lock);<br /> rlock(cpu_hotplug_lock);<br /> <br /> *** DEADLOCK ***<br /> <br /> 5 locks held by bash/46904:<br /> #0: ffff98f6c3bb23f0 (sb_writers#5){.+.+}-{0:0}, at: ksys_write+0x64/0xe0<br /> #1: ffff98f6c328e488 (&amp;of-&gt;mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0xf8/0x1d0<br /> #2: ffff98ef83b31890 (kn-&gt;active#113){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x100/0x1d0<br /> #3: ffffffffabf9db48 (mf_mutex){+.+.}-{3:3}, at: memory_failure+0x44/0xc70<br /> #4: ffffffffabf92ea8 (pcp_batch_high_lock){+.+.}-{3:3}, at: zone_pcp_disable+0x16/0x40<br /> <br /> stack backtrace:<br /> CPU: 10 PID: 46904 Comm: bash Kdump: loaded Not tainted 6.8.0-11409-gf6cef5f8c37f #1<br /> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014<br /> Call Trace:<br /> <br /> dump_stack_lvl+0x68/0xa0<br /> check_noncircular+0x129/0x140<br /> __lock_acquire+0x1298/0x1cd0<br /> lock_acquire+0xc0/0x2b0<br /> cpus_read_lock+0x2a/0xc0<br /> static_key_slow_dec+0x16/0x60<br /> __hugetlb_vmemmap_restore_folio+0x1b9/0x200<br /> dissolve_free_huge_page+0x211/0x260<br /> __page_handle_poison+0x45/0xc0<br /> memory_failure+0x65e/0xc70<br /> hard_offline_page_store+0x55/0xa0<br /> kernfs_fop_write_iter+0x12c/0x1d0<br /> vfs_write+0x387/0x550<br /> ksys_write+0x64/0xe0<br /> do_syscall_64+0xca/0x1e0<br /> entry_SYSCALL_64_after_hwframe+0x6d/0x75<br /> RIP: 0033:0x7fc862314887<br /> Code: 10 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b7 0f 1f 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 b8 01 00 00 00 0f 05 3d 00 f0 ff ff 77 51 c3 48 83 ec 28 48 89 54 24 18 48 89 74 24<br /> RSP: 002b:00007fff19311268 EFLAGS: 00000246 ORIG_RAX: 0000000000000001<br /> RAX: ffffffffffffffda RBX: 000000000000000c RCX: 00007fc862314887<br /> RDX: 000000000000000c RSI: 000056405645fe10 RDI: 0000000000000001<br /> RBP: 000056405645fe10 R08: 00007fc8623d1460 R09: 000000007fffffff<br /> R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000000c<br /> R13: 00007fc86241b780 R14: 00007fc862417600 R15: 00007fc862416a00<br /> <br /> In short, below scene breaks the <br /> ---truncated---