CVE-2024-48881: bcache: revert replacing IS_ERR_OR_NULL with IS_ERR again

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-01-11 · updated 2026-10-15
Weakness: CWE-476

Description

In the Linux kernel, the following vulnerability has been resolved: bcache: revert replacing IS_ERR_OR_NULL with IS_ERR again Commit 028ddcac477b ("bcache: Remove unnecessary NULL point check in node allocations") leads a NULL pointer deference in cache_set_flush(). 1721 if (!IS_ERR_OR_NULL(c->root)) 1722 list_add(&c->root->list, &c->btree_cache); >From the above code in cache_set_flush(), if previous registration code fails before allocating c->root, it is possible c->root is NULL as what it is initialized. __bch_btree_node_alloc() never returns NULL but c->root is possible to be NULL at above line 1721. This patch replaces IS_ERR() by IS_ERR_OR_NULL() to fix this.

Affected products

Linux kernel: from 4.19.291 before 4.20; from 5.4.251 before 5.4.287; from 5.10.188 before 5.10.231; from 5.15.121 before 5.15.174; from 6.1.39 before 6.1.120; from 6.4.4 before 6.6.66 — fixed in 4.20, 5.10.231, 5.15.174, 5.4.287, 6.1.120, 6.12.5

How to fix

Upgrade to a fixed version: Linux kernel 4.20, 5.10.231, 5.15.174, 5.4.287. Check the vendor advisory for mitigations.

References

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