Bug 2425101 (CVE-2022-50738)
| Summary: | CVE-2022-50738 kernel: Linux kernel: vhost-vdpa memory leak leading to Denial of Service | ||
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| Product: | [Other] Security Response | Reporter: | OSIDB Bzimport <bzimport> |
| Component: | vulnerability | Assignee: | Product Security DevOps Team <prodsec-dev> |
| Status: | NEW --- | QA Contact: | |
| Severity: | low | Docs Contact: | |
| Priority: | low | ||
| Version: | unspecified | Keywords: | Security |
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
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| Fixed In Version: | Doc Type: | --- | |
| Doc Text: |
A flaw was found in the Linux kernel's vhost-vdpa component. This memory leak vulnerability occurs when an application using vhost-vdpa fails to properly invalidate I/O Translation Lookaside Buffer (IOTLB) entries or crashes. A local attacker or application could exploit this flaw, leading to memory exhaustion and potentially a Denial of Service (DoS) on the affected system.
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Story Points: | --- |
| Clone Of: | Environment: | ||
| Last Closed: | Type: | --- | |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
In the Linux kernel, the following vulnerability has been resolved: vhost-vdpa: fix an iotlb memory leak Before commit 3d5698793897 ("vhost-vdpa: introduce asid based IOTLB") we called vhost_vdpa_iotlb_unmap(v, iotlb, 0ULL, 0ULL - 1) during release to free all the resources allocated when processing user IOTLB messages through vhost_vdpa_process_iotlb_update(). That commit changed the handling of IOTLB a bit, and we accidentally removed some code called during the release. We partially fixed this with commit 037d4305569a ("vhost-vdpa: call vhost_vdpa_cleanup during the release") but a potential memory leak is still there as showed by kmemleak if the application does not send VHOST_IOTLB_INVALIDATE or crashes: unreferenced object 0xffff888007fbaa30 (size 16): comm "blkio-bench", pid 914, jiffies 4294993521 (age 885.500s) hex dump (first 16 bytes): 40 73 41 07 80 88 ff ff 00 00 00 00 00 00 00 00 @sA............. backtrace: [<0000000087736d2a>] kmem_cache_alloc_trace+0x142/0x1c0 [<0000000060740f50>] vhost_vdpa_process_iotlb_msg+0x68c/0x901 [vhost_vdpa] [<0000000083e8e205>] vhost_chr_write_iter+0xc0/0x4a0 [vhost] [<000000008f2f414a>] vhost_vdpa_chr_write_iter+0x18/0x20 [vhost_vdpa] [<00000000de1cd4a0>] vfs_write+0x216/0x4b0 [<00000000a2850200>] ksys_write+0x71/0xf0 [<00000000de8e720b>] __x64_sys_write+0x19/0x20 [<0000000018b12cbb>] do_syscall_64+0x3f/0x90 [<00000000986ec465>] entry_SYSCALL_64_after_hwframe+0x63/0xcd Let's fix this calling vhost_vdpa_iotlb_unmap() on the whole range in vhost_vdpa_remove_as(). We move that call before vhost_dev_cleanup() since we need a valid v->vdev.mm in vhost_vdpa_pa_unmap(). vhost_iotlb_reset() call can be removed, since vhost_vdpa_iotlb_unmap() on the whole range removes all the entries. The kmemleak log reported was observed with a vDPA device that has `use_va` set to true (e.g. VDUSE). This patch has been tested with both types of devices.