CVE-2024-38540: linux kernel vulnerability

What is known

In the Linux kernel, the following vulnerability has been resolved: bnxt_re: avoid shift undefined behavior in bnxt_qplib_alloc_init_hwq Undefined behavior is triggered when bnxt_qplib_alloc_init_hwq is called with hwq_attr->aux_depth != 0 and hwq_attr->aux_stride == 0. In that case, "roundup_pow_of_two(hwq_attr->aux_stride)" gets called. roundup_pow_of_two is documented as undefined for 0. Fix it in the one caller that had this combination. The undefined behavior was detected by UBSAN: UBSAN: shift-out-of-bounds in ./include/linux/log2.h:57:13 shift exponent 64 is too large for 64-bit type 'long unsigned int' CPU: 24 PID: 1075 Comm: (udev-worker) Not tainted 6.9.0-rc6+ #4 Hardware name: Abacus electric, s.r.o. - servis@abacus.cz Super Server/H12SSW-iN, BIOS 2.7 10/25/2023 Call Trace: <TASK> dump_stack_lvl+0x5d/0x80 ubsan_epilogue+0x5/0x30 __ubsan_handle_shift_out_of_bounds.cold+0x61/0xec __roundup_pow_of_two+0x25/0x35 [bnxt_re] bnxt_qplib_alloc_init_hwq+0xa1/0x470 [bnxt_re] bnxt_qplib_create_qp+0x19e/0x840 [bnxt_re] bnxt_re_create_qp+0x9b1/0xcd0 [bnxt_re] ? srso_alias_return_thunk+0x5/0xfbef5 ? srso_alias_return_thunk+0x5/0xfbef5 ? __kmalloc+0x1b6/0x4f0 ? create_qp.part.0+0x128/0x1c0 [ib_core] ? __pfx_bnxt_re_create_qp+0x10/0x10 [bnxt_re] create_qp.part.0+0x128/0x1c0 [ib_core] ib_create_qp_kernel+0x50/0xd0 [ib_core] create_mad_qp+0x8e/0xe0 [ib_core] ? __pfx_qp_event_handler+0x10/0x10 [ib_core] ib_mad_init_device+0x2be/0x680 [ib_core] add_client_context+0x10d/0x1a0 [ib_core] enable_device_and_get+0xe0/0x1d0 [ib_core] ib_register_device+0x53c/0x630 [ib_core] ? srso_alias_return_thunk+0x5/0xfbef5 bnxt_re_probe+0xbd8/0xe50 [bnxt_re] ? __pfx_bnxt_re_probe+0x10/0x10 [bnxt_re] auxiliary_bus_probe+0x49/0x80 ? driver_sysfs_add+0x57/0xc0 really_probe+0xde/0x340 ? pm_runtime_barrier+0x54/0x90 ? __pfx___driver_attach+0x10/0x10 __driver_probe_device+0x78/0x110 driver_probe_device+0x1f/0xa0 __driver_attach+0xba/0x1c0 bus_for_each_dev+0x8f/0xe0 bus_add_driver+0x146/0x220 driver_register+0x72/0xd0 __auxiliary_driver_register+0x6e/0xd0 ? __pfx_bnxt_re_mod_init+0x10/0x10 [bnxt_re] bnxt_re_mod_init+0x3e/0xff0 [bnxt_re] ? __pfx_bnxt_re_mod_init+0x10/0x10 [bnxt_re] do_one_initcall+0x5b/0x310 do_init_module+0x90/0x250 init_module_from_file+0x86/0xc0 idempotent_init_module+0x121/0x2b0 __x64_sys_finit_module+0x5e/0xb0 do_syscall_64+0x82/0x160 ? srso_alias_return_thunk+0x5/0xfbef5 ? syscall_exit_to_user_mode_prepare+0x149/0x170 ? srso_alias_return_thunk+0x5/0xfbef5 ? syscall_exit_to_user_mode+0x75/0x230 ? srso_alias_return_thunk+0x5/0xfbef5 ? do_syscall_64+0x8e/0x160 ? srso_alias_return_thunk+0x5/0xfbef5 ? __count_memcg_events+0x69/0x100 ? srso_alias_return_thunk+0x5/0xfbef5 ? count_memcg_events.constprop.0+0x1a/0x30 ? srso_alias_return_thunk+0x5/0xfbef5 ? handle_mm_fault+0x1f0/0x300 ? srso_alias_return_thunk+0x5/0xfbef5 ? do_user_addr_fault+0x34e/0x640 ? srso_alias_return_thunk+0x5/0xfbef5 ? srso_alias_return_thunk+0x5/0xfbef5 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7f4e5132821d Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e3 db 0c 00 f7 d8 64 89 01 48 RSP: 002b:00007ffca9c906a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139 RAX: ffffffffffffffda RBX: 0000563ec8a8f130 RCX: 00007f4e5132821d RDX: 0000000000000000 RSI: 00007f4e518fa07d RDI: 000000000000003b RBP: 00007ffca9c90760 R08: 00007f4e513f6b20 R09: 00007ffca9c906f0 R10: 0000563ec8a8faa0 R11: 0000000000000246 R12: 00007f4e518fa07d R13: 0000000000020000 R14: 0000563ec8409e90 R15: 0000563ec8a8fa60 </TASK> ---[ end trace ]---

Business impact

Successful exploitation of CVE-2024-38540, a medium vulnerability (CVSS 4.4) affecting linux kernel, may affect the confidentiality, integrity or availability of the vulnerable environment. The exact impact depends on the installed version, exposed interfaces and deployment configuration.

Recommended administrator action

Confirm whether linux kernel is present and compare installed versions with the vendor advisory and NVD record. Apply the vendor patch or documented mitigation; until remediation is complete, reduce exposure of affected interfaces, review relevant logs and monitor for indicators of exploitation. DataHouse can support version verification, managed patching, network exposure reduction, log review and backup validation for dedicated, cloud and colocated environments.

Sources

• NVD
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