Bug 2516501 (CVE-2026-72098)

Summary: CVE-2026-72098 kernel: dm-verity: fix buffer overflow in FEC calculation
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: high    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the dm-verity component of the Linux kernel. A buffer overflow occurs during Forward Error Correction (FEC) calculation, allowing an attacker to write past the end of an allocated buffer. This out-of-bounds write can corrupt the syndrome buffer, potentially leading to system instability or other undefined behavior.
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Description OSIDB Bzimport 2026-08-15 06:15:48 UTC 
In the Linux kernel, the following vulnerability has been resolved:

dm-verity: fix buffer overflow in FEC calculation

There's a buffer overflow in dm-verity-fec:

if (neras && *neras <= v->fec->roots)
	fio->erasures[(*neras)++] = i;

This allows *neras to reach roots + 1 (the post-increment pushes it past
roots). This value is then passed as no_eras to decode_rs8(). Inside the
RS decoder (lib/reed_solomon/decode_rs.c:113-121), the erasure locator
polynomial loop writes lambda[j] where j can reach nroots + 1 — one
element past the end of lambda[] (which is sized nroots + 1, valid
indices 0..nroots). The out-of-bounds write lands on syn[0], corrupting
the syndrome buffer.
Comment 1 Keith Grant 2026-08-17 21:29:49 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081524-CVE-2026-72098-cbda@gregkh/T