CVE-2024-36916: blk-iocost: avoid out of bounds shift

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-05-30 · updated 2026-10-15
Weakness: CWE-125

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 undefined value delay will be, but I suspect it could be more than a little annoying to debug.

Affected products

Debian Linux: 10.0
Linux kernel: from 5.10 before 5.10.217; from 5.11 before 5.15.159; from 5.16 before 6.1.91; from 6.2 before 6.6.31; from 6.7 before 6.8.10; 6.9-rc1, 6.9-rc2, 6.9-rc3 — fixed in 5.10.217, 5.15.159, 6.1.91, 6.6.31, 6.8.10

How to fix

Upgrade to a fixed version: Linux kernel 5.10.217, 5.15.159, 6.1.91, 6.6.31. Check the vendor advisory for mitigations.

References

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