CVE-2021-46956 virtiofs: fix memory leak in virtio_fs_probe()
A memory leak in the Linux kernel virtiofs driver can lead to resource exhaustion and denial of service when duplicate tags are passed.
- 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-2021-46956?
CVE-2021-46956 is a medium-severity memory corruption vulnerability in Linux kernel, published on 27 Feb 2024. 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:
virtiofs: fix memory leak in virtio_fs_probe()
When accidentally passing twice the same tag to qemu, kmemleak ended up reporting a memory leak in virtiofs. Also, looking at the log I saw the following error (that's when I realised the duplicated tag):
virtiofs: probe of virtio5 failed with error -17
Here's the kmemleak log for reference:
unreferenced object 0xffff888103d47800 (size 1024): comm "systemd-udevd", pid 118, jiffies 4294893780 (age 18.340s) hex dump (first 32 bytes): 00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... ff ff ff ff ff ff ff ff 80 90 02 a0 ff ff ff ff ................ backtrace: [<000000000ebb87c1>] virtio_fs_probe+0x171/0x7ae [virtiofs] [<00000000f8aca419>] virtio_dev_probe+0x15f/0x210 [<000000004d6baf3c>] really_probe+0xea/0x430 [<00000000a6ceeac8>] device_driver_attach+0xa8/0xb0 [<00000000196f47a7>] __driver_attach+0x98/0x140 [<000000000b20601d>] bus_for_each_dev+0x7b/0xc0 [<00000000399c7b7f>] bus_add_driver+0x11b/0x1f0 [<0000000032b09ba7>] driver_register+0x8f/0xe0 [<00000000cdd55998>] 0xffffffffa002c013 [<000000000ea196a2>] do_one_initcall+0x64/0x2e0 [<0000000008f727ce>] do_init_module+0x5c/0x260 [<000000003cdedab6>] __do_sys_finit_module+0xb5/0x120 [<00000000ad2f48c6>] do_syscall_64+0x33/0x40 [<00000000809526b5>] entry_SYSCALL_64_after_hwframe+0x44/0xae
Weakness: CWE-401
Which versions are affected by CVE-2021-46956?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2021-46956?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2021-46956 being exploited?
There is no known exploitation of CVE-2021-46956 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2021-46956, GHSA-7r25-m49h-vw58, UBUNTU-CVE-2021-46956.