CVE-2022-49993: loop: Check for overflow while configuring loop

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-06-18 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: loop: Check for overflow while configuring loop The userspace can configure a loop using an ioctl call, wherein a configuration of type loop_config is passed (see lo_ioctl()'s case on line 1550 of drivers/block/loop.c). This proceeds to call loop_configure() which in turn calls loop_set_status_from_info() (see line 1050 of loop.c), passing &config->info which is of type loop_info64*. This function then sets the appropriate values, like the offset. loop_device has lo_offset of type loff_t (see line 52 of loop.c), which is typdef-chained to long long, whereas loop_info64 has lo_offset of type __u64 (see line 56 of include/uapi/linux/loop.h). The function directly copies offset from info to the device as follows (See line 980 of loop.c): lo->lo_offset = info->lo_offset; This results in an overflow, which triggers a warning in iomap_iter() due to a call to iomap_iter_done() which has: WARN_ON_ONCE(iter->iomap.offset > iter->pos); Thus, check for negative value during loop_set_status_from_info(). Bug report: https://syzkaller.appspot.com/bug?id=c620fe14aac810396d3c3edc9ad73848bf69a29e

Affected products

Linux kernel: before 4.9.327; from 4.10 before 4.14.292; from 4.15 before 4.19.312; from 4.20 before 5.4.274; from 5.5 before 5.10.140; from 5.11 before 5.15.64 — fixed in 4.14.292, 4.19.312, 4.9.327, 5.10.140, 5.15.64, 5.19.6

How to fix

Upgrade to a fixed version: Linux kernel 4.14.292, 4.19.312, 4.9.327, 5.10.140. Check the vendor advisory for mitigations.

References

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