Bug 2327170 (CVE-2024-50279)
| Summary: | CVE-2024-50279 kernel: dm cache: fix out-of-bounds access to the dirty bitset when resizing | ||
|---|---|---|---|
| Product: | [Other] Security Response | Reporter: | OSIDB Bzimport <bzimport> |
| Component: | vulnerability | Assignee: | Product Security DevOps Team <prodsec-dev> |
| Status: | NEW --- | QA Contact: | |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | unspecified | CC: | dfreiber, drow, jburrell, vkumar |
| Target Milestone: | --- | Keywords: | Security |
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | If docs needed, set a value | |
| Doc Text: | 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: | |||
| Bug Depends On: | 2327250 | ||
| Bug Blocks: | |||
In the Linux kernel, the following vulnerability has been resolved: dm cache: fix out-of-bounds access to the dirty bitset when resizing dm-cache checks the dirty bits of the cache blocks to be dropped when shrinking the fast device, but an index bug in bitset iteration causes out-of-bounds access. Reproduce steps: 1. create a cache device of 1024 cache blocks (128 bytes dirty bitset) dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" dmsetup create cdata --table "0 131072 linear /dev/sdc 8192" dmsetup create corig --table "0 524288 linear /dev/sdc 262144" dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct dmsetup create cache --table "0 524288 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0" 2. shrink the fast device to 512 cache blocks, triggering out-of-bounds access to the dirty bitset (offset 0x80) dmsetup suspend cache dmsetup reload cdata --table "0 65536 linear /dev/sdc 8192" dmsetup resume cdata dmsetup resume cache KASAN reports: BUG: KASAN: vmalloc-out-of-bounds in cache_preresume+0x269/0x7b0 Read of size 8 at addr ffffc900000f3080 by task dmsetup/131 (...snip...) The buggy address belongs to the virtual mapping at [ffffc900000f3000, ffffc900000f5000) created by: cache_ctr+0x176a/0x35f0 (...snip...) Memory state around the buggy address: ffffc900000f2f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc900000f3000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffffc900000f3080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ^ ffffc900000f3100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc900000f3180: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 Fix by making the index post-incremented.