Bug 2541150 (CVE-2026-97614)

Summary: CVE-2026-97614 kernel: net: dsa: tag_brcm: legacy FCS: request needed tailroom
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Distributed Switch Architecture (DSA) Broadcom tagger. The legacy Frame Check Sequence (FCS) tag handler failed to declare the required buffer tailroom, allowing non-linear network packet buffers to reach the checksum calculation routine. A local user could exploit this flaw by transmitting specially crafted network traffic, triggering an out-of-bounds memory read. This issue primarily leads to a kernel crash, resulting in a Denial of Service (DoS), or the potential disclosure of sensitive memory.
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Description OSIDB Bzimport 2026-09-25 10:52:29 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net: dsa: tag_brcm: legacy FCS: request needed tailroom

The legacy FCS tagger calculates the CRC over skb->len bytes starting at
skb->data. When a nonlinear skb reaches the tagger, this reads past the
linear head into unrelated slab memory.

The tagger appends an Ethernet FCS but does not declare that tailroom. As a
result, DSA leaves NETIF_F_SG and NETIF_F_FRAGLIST enabled on the user
port, and nonlinear skbs can reach the CRC calculation.

Declare the required tailroom. DSA will then clear those features and the
networking core will linearize skbs before the tagger runs.

A KASAN-enabled dsa_loop test using this tagger reports:

  BUG: KASAN: slab-out-of-bounds in crc32_le
  Read of size 1 at addr ffff8880397086c0 by task exp/135

  Call Trace:
   crc32_le (lib/crc/crc32-main.c:38)
   brcm_leg_fcs_tag_xmit (net/dsa/tag_brcm.c:343)
   dsa_user_xmit (net/dsa/user.c:942)
   dev_hard_start_xmit (net/core/dev.c:3937)
   __dev_queue_xmit (net/core/dev.c:4926)
   packet_sendmsg (net/packet/af_packet.c:3110)
   __sys_sendto (net/socket.c:2281)

  The buggy address belongs to the object at ffff888039708400
   which belongs to the cache skbuff_small_head of size 704
  The buggy address is located 0 bytes to the right of
   allocated 704-byte region [ffff888039708400, ffff8880397086c0)
Comment 1 Keith Grant 2026-09-29 15:08:56 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-97614.mbox