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CVE-2026-46130 (GCVE-0-2026-46130)

Vulnerability from cvelistv5 – Published: 2026-05-28 09:35 – Updated: 2026-08-03 09:32
VLAI
Title
dm-verity-fec: fix reading parity bytes split across blocks (take 3)
Summary
In the Linux kernel, the following vulnerability has been resolved: dm-verity-fec: fix reading parity bytes split across blocks (take 3) fec_decode_bufs() assumes that the parity bytes of the first RS codeword it decodes are never split across parity blocks. This assumption is false. Consider v->fec->block_size == 4096 && v->fec->roots == 17 && fio->nbufs == 1, for example. In that case, each call to fec_decode_bufs() consumes v->fec->roots * (fio->nbufs << DM_VERITY_FEC_BUF_RS_BITS) = 272 parity bytes. Considering that the parity data for each message block starts on a block boundary, the byte alignment in the parity data will iterate through 272*i mod 4096 until the 3 parity blocks have been consumed. On the 16th call (i=15), the alignment will be 4080 bytes into the first block. Only 16 bytes remain in that block, but 17 parity bytes will be needed. The code reads out-of-bounds from the parity block buffer. Fortunately this doesn't normally happen, since it can occur only for certain non-default values of fec_roots *and* when the maximum number of buffers couldn't be allocated due to low memory. For example with block_size=4096 only the following cases are affected: fec_roots=17: nbufs in [1, 3, 5, 15] fec_roots=19: nbufs in [1, 229] fec_roots=21: nbufs in [1, 3, 5, 13, 15, 39, 65, 195] fec_roots=23: nbufs in [1, 89] Regardless, fix it by refactoring how the parity blocks are read.
Severity
7.1 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 6df90c02bae468a3a6110bafbc659884d0c4966c , < d47281b9a4472cfd73122393e79fbe76b651e46a (git)
Affected: 6df90c02bae468a3a6110bafbc659884d0c4966c , < 3d1b4e2d8ac0a1a1390a117f61ce0ca1c47e3bcb (git)
Affected: 6df90c02bae468a3a6110bafbc659884d0c4966c , < 430a05cb926f6bdf53e81460a2c3a553257f3f61 (git)
Affected: 6bc6ee31113b05db605694491bdeb2b1730142f1 (git)
Affected: 12caa73a28f0ae147ec0356b45091edf2462462b (git)
Affected: fc8943886629e26de34867db302c74d465510826 (git)
Affected: 6.1.125 , < 6.2 (semver)
Affected: 6.6.72 , < 6.7 (semver)
Affected: 6.12.10 , < 6.13 (semver)
guessed Create a notification for this product.
Linux Linux Affected: 6.13
Unaffected: 0 , < 6.13 (semver)
Unaffected: 6.18.42 , ≤ 6.18.* (semver)
Unaffected: 7.0.7 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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