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CVE-2026-89576: dm-era: fix shadowed superblock leak on take-snap failure

• Severity: unknown
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-11 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: dm-era: fix shadowed superblock leak on take-snap failure metadata_take_snap() bumps the live superblock refcount and then dm_tm_shadow_block() allocates a new block for the metadata snapshot. If the subsequent dm_sm_inc_block() of writeset_tree_root or era_array_root fails, the function only unlocks the clone and returns. The newly allocated shadow block is never returned to the metadata space map, so each failed take-snap permanently leaks one metadata block. Free the clone with dm_sm_dec_block() on those error paths, matching the final step of metadata_drop_snap().

Affected products

• Linux kernel: 3.15 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux kernel 7.3. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/36ff918637e3517f732188a3c39dbeae5b9cfb1b
• https://git.kernel.org/stable/c/39c5aa3bd8ec3912d2cd0b3fe092642b0d2b0713
• https://git.kernel.org/stable/c/54dd21ca945ecc07885012b9f3e8197f091cfba0
• https://git.kernel.org/stable/c/6876ca330e741fb8886d12070cb6a7f9cb67257e
• https://git.kernel.org/stable/c/d66ceeefb87ddb097b0546bafc581380b816b048
• https://git.kernel.org/stable/c/dc731d7fddfd6149f5e88ea080475d18c36d3c64
• https://git.kernel.org/stable/c/e9fa68b89214bc65af0ef963af7ec3cce9f866e0
• https://git.kernel.org/stable/c/ef00efb6fcaee88f50891279ceced17c614e97f7

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