CVE-2023-54020
Description
In the Linux kernel, the following vulnerability has been resolved:
dmaengine: sf-pdma: pdma_desc memory leak fix
Commit b2cc5c465c2c ("dmaengine: sf-pdma: Add multithread support for a DMA channel") changed sf_pdma_prep_dma_memcpy() to unconditionally allocate a new sf_pdma_desc each time it is called.
The driver previously recycled descs, by checking the in_use flag, only allocating additional descs if the existing one was in use. This logic was removed in commit b2cc5c465c2c ("dmaengine: sf-pdma: Add multithread support for a DMA channel"), but sf_pdma_free_desc() was not changed to handle the new behaviour.
As a result, each time sf_pdma_prep_dma_memcpy() is called, the previous descriptor is leaked, over time leading to memory starvation:
unreferenced object 0xffffffe008447300 (size 192): comm "irq/39-mchp_dsc", pid 343, jiffies 4294906910 (age 981.200s) hex dump (first 32 bytes): 00 00 00 ff 00 00 00 00 b8 c1 00 00 00 00 00 00 ................ 00 00 70 08 10 00 00 00 00 00 00 c0 00 00 00 00 ..p............. backtrace: [<00000000064a04f4>] kmemleak_alloc+0x1e/0x28 [<00000000018927a7>] kmem_cache_alloc+0x11e/0x178 [<000000002aea8d16>] sf_pdma_prep_dma_memcpy+0x40/0x112
Add the missing kfree() to sf_pdma_free_desc(), and remove the redundant in_use flag.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Missing kfree() in sf_pdma_free_desc() causes memory leak in Linux kernel's sf-pdma driver after commit b2cc5c465c2c introduced dynamic allocation.
Vulnerability
Overview
A memory leak exists in the Linux kernel's sf-pdma driver (dmaengine). Commit b2cc5c465c2c changed sf_pdma_prep_dma_memcpy() to unconditionally allocate a new sf_pdma_desc structure via kmem_cache_alloc(), removing previous logic that recycled descriptors using an in_use flag. However, sf_pdma_free_desc() was not updated to kfree() the descriptor; it left the deallocation incomplete, causing each allocation to leak memory. [1]
Exploitation
Conditions
This vulnerability is triggered by repeated calls to sf_pdma_prep_dma_memcpy() without corresponding proper free. It manifests over time, leading to gradual memory exhaustion. No special privileges are required beyond the ability to trigger DMA operations through the driver interface. [1]
Impact
An attacker or even legitimate sustained usage can cause memory starvation, potentially leading to denial-of-service (system instability or crash). The kernel memory leak is visible via kmemleak reports showing unreferenced objects of size 192 bytes. [1]
Mitigation
The fix is included in Linux kernel stable updates. It adds the missing kfree() call in sf_pdma_free_desc() and removes the now-redundant in_use flag. Users should apply the latest kernel updates from their distribution. [1]
AI Insight generated on May 19, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.
Affected products
1Patches
4ad222c9af25e03fece43fa108bd5040bd43fb02e07015a5aVulnerability mechanics
Generated on May 9, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.
References
4News mentions
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