CVE-2024-49933: blk_iocost: fix more out of bound shifts

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-10-21 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: blk_iocost: fix more out of bound shifts Recently running UBSAN caught few out of bound shifts in the ioc_forgive_debts() function: UBSAN: shift-out-of-bounds in block/blk-iocost.c:2142:38 shift exponent 80 is too large for 64-bit type 'u64' (aka 'unsigned long long') ... UBSAN: shift-out-of-bounds in block/blk-iocost.c:2144:30 shift exponent 80 is too large for 64-bit type 'u64' (aka 'unsigned long long') ... Call Trace: <IRQ> dump_stack_lvl+0xca/0x130 __ubsan_handle_shift_out_of_bounds+0x22c/0x280 ? __lock_acquire+0x6441/0x7c10 ioc_timer_fn+0x6cec/0x7750 ? blk_iocost_init+0x720/0x720 ? call_timer_fn+0x5d/0x470 call_timer_fn+0xfa/0x470 ? blk_iocost_init+0x720/0x720 __run_timer_base+0x519/0x700 ... Actual impact of this issue was not identified but I propose to fix the undefined behaviour. The proposed fix to prevent those out of bound shifts consist of precalculating exponent before using it the shift operations by taking min value from the actual exponent and maximum possible number of bits.

Affected products

Linux kernel: before 5.10.227; from 5.11 before 5.15.168; from 5.16 before 6.1.113; from 6.2 before 6.6.55; from 6.7 before 6.10.14; from 6.11 before 6.11.3 — fixed in 5.10.227, 5.15.168, 6.1.113, 6.10.14, 6.11.3, 6.6.55

How to fix

Upgrade to a fixed version: Linux kernel 5.10.227, 5.15.168, 6.1.113, 6.10.14. Check the vendor advisory for mitigations.

References

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