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

Summary

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().

Timeline

1. Sep 11, 2026, 7:44 PM UTCCVE published
2. Oct 19, 2026, 8:49 AM UTCRecord last updated

Affected versions

• Linux Linux

  From eec40579d84873dfb7021eb24c50360f073237c5 · fixed in 54dd21ca945ecc07885012b9f3e8197f091cfba0; From eec40579d84873dfb7021eb24c50360f073237c5 · fixed in ef00efb6fcaee88f50891279ceced17c614e97f7; From eec40579d84873dfb7021eb24c50360f073237c5 · fixed in e9fa68b89214bc65af0ef963af7ec3cce9f866e0; From eec40579d84873dfb7021eb24c50360f073237c5 · fixed in dc731d7fddfd6149f5e88ea080475d18c36d3c64; From eec40579d84873dfb7021eb24c50360f073237c5 · fixed in d66ceeefb87ddb097b0546bafc581380b816b048; From eec40579d84873dfb7021eb24c50360f073237c5 · fixed in 36ff918637e3517f732188a3c39dbeae5b9cfb1b; From eec40579d84873dfb7021eb24c50360f073237c5 · fixed in 6876ca330e741fb8886d12070cb6a7f9cb67257e; From eec40579d84873dfb7021eb24c50360f073237c5 · fixed in 39c5aa3bd8ec3912d2cd0b3fe092642b0d2b0713

• Linux Linux

  3.15

• KernelLinux

  From 3.15.0 · fixed in 5.10.270; From 5.11.0 · fixed in 5.15.221; From 5.16.0 · fixed in 6.1.188; From 6.2.0 · fixed in 6.6.157; From 6.7.0 · fixed in 6.12.109; From 6.13.0 · fixed in 6.18.50; From 6.19.0 · fixed in 7.2.4

References 8