CVE-2022-49993 loop: Check for overflow while configuring loop
A local attacker can trigger a kernel warning and potential denial of service by configuring a loop device with an offset causing integer overflow.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2022-49993?
CVE-2022-49993 is a medium-severity vulnerability in Linux kernel, published on 18 Jun 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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
Which versions are affected by CVE-2022-49993?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2022-49993?
Apply the vendor's patch.
Is CVE-2022-49993 being exploited?
There is no known exploitation of CVE-2022-49993 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2022-49993, GHSA-x3g2-qmp5-mx6f, UBUNTU-CVE-2022-49993.