CVE-2023-53629

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

fs: dlm: fix use after free in midcomms commit

While working on processing dlm message in softirq context I experienced the following KASAN use-after-free warning:

[ 151.760477] ================================================================== [ 151.761803] BUG: KASAN: use-after-free in dlm_midcomms_commit_mhandle+0x19d/0x4b0 [ 151.763414] Read of size 4 at addr ffff88811a980c60 by task lock_torture/1347

[ 151.765284] CPU: 7 PID: 1347 Comm: lock_torture Not tainted 6.1.0-rc4+ #2828 [ 151.766778] Hardware name: Red Hat KVM/RHEL-AV, BIOS 1.16.0-3.module+el8.7.0+16134+e5908aa2 04/01/2014 [ 151.768726] Call Trace: [ 151.769277] [ 151.769748] dump_stack_lvl+0x5b/0x86 [ 151.770556] print_report+0x180/0x4c8 [ 151.771378] ? kasan_complete_mode_report_info+0x7c/0x1e0 [ 151.772241] ? dlm_midcomms_commit_mhandle+0x19d/0x4b0 [ 151.773069] kasan_report+0x93/0x1a0 [ 151.773668] ? dlm_midcomms_commit_mhandle+0x19d/0x4b0 [ 151.774514] __asan_load4+0x7e/0xa0 [ 151.775089] dlm_midcomms_commit_mhandle+0x19d/0x4b0 [ 151.775890] ? create_message.isra.29.constprop.64+0x57/0xc0 [ 151.776770] send_common+0x19f/0x1b0 [ 151.777342] ? remove_from_waiters+0x60/0x60 [ 151.778017] ? lock_downgrade+0x410/0x410 [ 151.778648] ? __this_cpu_preempt_check+0x13/0x20 [ 151.779421] ? rcu_lockdep_current_cpu_online+0x88/0xc0 [ 151.780292] _convert_lock+0x46/0x150 [ 151.780893] convert_lock+0x7b/0xc0 [ 151.781459] dlm_lock+0x3ac/0x580 [ 151.781993] ? 0xffffffffc0540000 [ 151.782522] ? torture_stop+0x120/0x120 [dlm_locktorture] [ 151.783379] ? dlm_scan_rsbs+0xa70/0xa70 [ 151.784003] ? preempt_count_sub+0xd6/0x130 [ 151.784661] ? is_module_address+0x47/0x70 [ 151.785309] ? torture_stop+0x120/0x120 [dlm_locktorture] [ 151.786166] ? 0xffffffffc0540000 [ 151.786693] ? lockdep_init_map_type+0xc3/0x360 [ 151.787414] ? 0xffffffffc0540000 [ 151.787947] torture_dlm_lock_sync.isra.3+0xe9/0x150 [dlm_locktorture] [ 151.789004] ? torture_stop+0x120/0x120 [dlm_locktorture] [ 151.789858] ? 0xffffffffc0540000 [ 151.790392] ? lock_torture_cleanup+0x20/0x20 [dlm_locktorture] [ 151.791347] ? delay_tsc+0x94/0xc0 [ 151.791898] torture_ex_iter+0xc3/0xea [dlm_locktorture] [ 151.792735] ? torture_start+0x30/0x30 [dlm_locktorture] [ 151.793606] lock_torture+0x177/0x270 [dlm_locktorture] [ 151.794448] ? torture_dlm_lock_sync.isra.3+0x150/0x150 [dlm_locktorture] [ 151.795539] ? lock_torture_stats+0x80/0x80 [dlm_locktorture] [ 151.796476] ? do_raw_spin_lock+0x11e/0x1e0 [ 151.797152] ? mark_held_locks+0x34/0xb0 [ 151.797784] ? _raw_spin_unlock_irqrestore+0x30/0x70 [ 151.798581] ? __kthread_parkme+0x79/0x110 [ 151.799246] ? trace_preempt_on+0x2a/0xf0 [ 151.799902] ? __kthread_parkme+0x79/0x110 [ 151.800579] ? preempt_count_sub+0xd6/0x130 [ 151.801271] ? __kasan_check_read+0x11/0x20 [ 151.801963] ? __kthread_parkme+0xec/0x110 [ 151.802630] ? lock_torture_stats+0x80/0x80 [dlm_locktorture] [ 151.803569] kthread+0x192/0x1d0 [ 151.804104] ? kthread_complete_and_exit+0x30/0x30 [ 151.804881] ret_from_fork+0x1f/0x30 [ 151.805480]

[ 151.806111] Allocated by task 1347: [ 151.806681] kasan_save_stack+0x26/0x50 [ 151.807308] kasan_set_track+0x25/0x30 [ 151.807920] kasan_save_alloc_info+0x1e/0x30 [ 151.808609] __kasan_slab_alloc+0x63/0x80 [ 151.809263] kmem_cache_alloc+0x1ad/0x830 [ 151.809916] dlm_allocate_mhandle+0x17/0x20 [ 151.810590] dlm_midcomms_get_mhandle+0x96/0x260 [ 151.811344] _create_message+0x95/0x180 [ 151.811994] create_message.isra.29.constprop.64+0x57/0xc0 [ 151.812880] send_common+0x129/0x1b0 [ 151.813467] _convert_lock+0x46/0x150 [ 151.814074] convert_lock+0x7b/0xc0 [ 151.814648] dlm_lock+0x3ac/0x580 [ 151.815199] torture_dlm_lock_sync.isra.3+0xe9/0x150 [dlm_locktorture] [ 151.816258] torture_ex_iter+0xc3/0xea [dlm_locktorture] [ 151.817129] lock_t —truncated—

Weakness

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.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/724b6bab0d75f1dc01fdfbf7fe8d4217a5cb90ba
• https://git.kernel.org/stable/c/a2de9f9b686c71b4fa3663ae374f5f643c46a446
• https://git.kernel.org/stable/c/a3b0e9ac3c2447008db942d51f593841d8329e99