CVE-2024-36916

/// Technical description

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

blk-iocost: avoid out of bounds shift

UBSAN catches undefined behavior in blk-iocost, where sometimes

iocg->delay is shifted right by a number that is too large,

resulting in undefined behavior on some architectures.

[ 186.556576] ------------[ cut here ]------------

UBSAN: shift-out-of-bounds in block/blk-iocost.c:1366:23

shift exponent 64 is too large for 64-bit type 'u64' (aka 'unsigned long long')

CPU: 16 PID: 0 Comm: swapper/16 Tainted: G S E N 6.9.0-0_fbk700_debug_rc2_kbuilder_0_gc85af715cac0 #1

Hardware name: Quanta Twin Lakes MP/Twin Lakes Passive MP, BIOS F09_3A23 12/08/2020

Call Trace:

<IRQ>

dump_stack_lvl+0x8f/0xe0

__ubsan_handle_shift_out_of_bounds+0x22c/0x280

iocg_kick_delay+0x30b/0x310

ioc_timer_fn+0x2fb/0x1f80

__run_timer_base+0x1b6/0x250

...

Avoid that undefined behavior by simply taking the

"delay = 0" branch if the shift is too large.

I am not sure what the symptoms of an undef

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References