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20 lines
2.7 KiB
Markdown
20 lines
2.7 KiB
Markdown
### [CVE-2024-50278](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-50278)
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### Description
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In the Linux kernel, the following vulnerability has been resolved:dm cache: fix potential out-of-bounds access on the first resumeOut-of-bounds access occurs if the fast device is expanded unexpectedlybefore the first-time resume of the cache table. This happens becauseexpanding the fast device requires reloading the cache table forcache_create to allocate new in-core data structures that fit the newsize, and the check in cache_preresume is not performed during thefirst resume, leading to the issue.Reproduce steps:1. prepare component devices:dmsetup create cmeta --table "0 8192 linear /dev/sdc 0"dmsetup create cdata --table "0 65536 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=direct2. load a cache table of 512 cache blocks, and deliberately expand the fast device before resuming the cache, making the in-core data structures inadequate.dmsetup create cache --notabledmsetup reload cache --table "0 524288 cache /dev/mapper/cmeta \/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0"dmsetup reload cdata --table "0 131072 linear /dev/sdc 8192"dmsetup resume cdatadmsetup resume cache3. suspend the cache to write out the in-core dirty bitset and hint array, leading to out-of-bounds access to the dirty bitset at offset 0x40:dmsetup suspend cacheKASAN reports: BUG: KASAN: vmalloc-out-of-bounds in is_dirty_callback+0x2b/0x80 Read of size 8 at addr ffffc90000085040 by task dmsetup/90 (...snip...) The buggy address belongs to the virtual mapping at [ffffc90000085000, ffffc90000087000) created by: cache_ctr+0x176a/0x35f0 (...snip...) Memory state around the buggy address: ffffc90000084f00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc90000084f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 >ffffc90000085000: 00 00 00 00 00 00 00 00 f8 f8 f8 f8 f8 f8 f8 f8 ^ ffffc90000085080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ffffc90000085100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8Fix by checking the size change on the first resume.
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### POC
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#### Reference
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No PoCs from references.
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#### Github
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- https://github.com/w4zu/Debian_security
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