Bug 2356601 (CVE-2025-21954)

Summary: CVE-2025-21954 kernel: netmem: prevent TX of unreadable skbs
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: low    
Version: unspecifiedCC: dfreiber, drow, jburrell, rhel-process-autobot, vkumar, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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Description OSIDB Bzimport 2025-04-01 16:01:54 UTC 
In the Linux kernel, the following vulnerability has been resolved:

netmem: prevent TX of unreadable skbs

Currently on stable trees we have support for netmem/devmem RX but not
TX. It is not safe to forward/redirect an RX unreadable netmem packet
into the device's TX path, as the device may call dma-mapping APIs on
dma addrs that should not be passed to it.

Fix this by preventing the xmit of unreadable skbs.

Tested by configuring tc redirect:

sudo tc qdisc add dev eth1 ingress
sudo tc filter add dev eth1 ingress protocol ip prio 1 flower ip_proto \
	tcp src_ip 192.168.1.12 action mirred egress redirect dev eth1

Before, I see unreadable skbs in the driver's TX path passed to dma
mapping APIs.

After, I don't see unreadable skbs in the driver's TX path passed to dma
mapping APIs.
Comment 1 Robb Gatica 2025-04-02 04:33:35 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025040143-CVE-2025-21954-8f0d@gregkh/T