CVE-2021-47353: udf: Fix NULL pointer dereference in udf_symlink function

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: 2024-05-21 · updated 2026-06-17
Weakness: CWE-476

Description

In the Linux kernel, the following vulnerability has been resolved: udf: Fix NULL pointer dereference in udf_symlink function In function udf_symlink, epos.bh is assigned with the value returned by udf_tgetblk. The function udf_tgetblk is defined in udf/misc.c and returns the value of sb_getblk function that could be NULL. Then, epos.bh is used without any check, causing a possible NULL pointer dereference when sb_getblk fails. This fix adds a check to validate the value of epos.bh.

Affected products

Linux kernel: before 4.4.276; from 4.5 before 4.9.276; from 4.10 before 4.14.240; from 4.15 before 4.19.198; from 4.20 before 5.4.133; from 5.5 before 5.10.51 — fixed in 4.14.240, 4.19.198, 4.4.276, 4.9.276, 5.10.51, 5.12.18

How to fix

Upgrade to a fixed version: Linux kernel 4.14.240, 4.19.198, 4.4.276, 4.9.276. Check the vendor advisory for mitigations.

References

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