jbd2: fix integer underflow in jbd2_journal_initialize_fast_commit()
jbd2_journal_initialize_fast_commit() validates journal capacity by
checking (journal->j_last - num_fc_blks < JBD2_MIN_JOURNAL_BLOCKS).
Both j_last and num_fc_blks are unsigned, so when num_fc_blks exceeds
j_last the subtraction wraps to a large value, bypassing the bounds
check.
The resulting underflow corrupts j_last, j_fc_first, and j_free,
leading to journal abort.
Fix by checking num_fc_blks against j_last before the subtraction,
returning -EFSCORRUPTED.
Analysis
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Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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No vendor fix or workaround currently provided.
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Sat, 15 Aug 2026 10:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-190 |
Sat, 15 Aug 2026 06:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: jbd2: fix integer underflow in jbd2_journal_initialize_fast_commit() jbd2_journal_initialize_fast_commit() validates journal capacity by checking (journal->j_last - num_fc_blks < JBD2_MIN_JOURNAL_BLOCKS). Both j_last and num_fc_blks are unsigned, so when num_fc_blks exceeds j_last the subtraction wraps to a large value, bypassing the bounds check. The resulting underflow corrupts j_last, j_fc_first, and j_free, leading to journal abort. Fix by checking num_fc_blks against j_last before the subtraction, returning -EFSCORRUPTED. | |
| Title | jbd2: fix integer underflow in jbd2_journal_initialize_fast_commit() | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-08-15T05:54:17.541Z
Reserved: 2026-08-09T03:40:39.913Z
Link: CVE-2026-72225
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-08-15T06:21:41.487
Modified: 2026-08-15T06:21:41.487
Link: CVE-2026-72225
Redhat
No data.
OpenCVE Enrichment
Updated: 2026-08-15T09:45:03Z