Bug 2536332 (CVE-2026-90115)

Summary: CVE-2026-90115 kernel: xsk: fix NULL pointer dereference in __xsk_rcv()
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 AF_XDP (xsk) socket multi-buffer receive path. This vulnerability allows for a NULL pointer dereference in the `__xsk_rcv()` function due to improper handling of buffer allocation failures. An attacker could exploit this flaw to cause a system crash, leading to a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-09-17 17:24:48 UTC 
In the Linux kernel, the following vulnerability has been resolved:

xsk: fix NULL pointer dereference in __xsk_rcv()

In the __xsk_rcv() multi-buffer path, xsk_buff_alloc() is called in a
loop without checking its return value. xsk_buff_can_alloc() only
counts fill queue entries without validating their addresses, so it
can succeed while xsk_buff_alloc() rejects all remaining entries and
returns NULL.

  Oops: general protection fault, probably for non-canonical address
   0xdffffc0000000000
  KASAN: null-ptr-deref in range
   [0x0000000000000000-0x0000000000000007]
  RIP: 0010:__xsk_rcv+0x426/0xc20 (net/xdp/xsk.c:350)
  Call Trace:
   xsk_generic_rcv+0x26d/0x5f0
   xdp_do_generic_redirect+0x3c5/0xcf0
   do_xdp_generic+0x92f/0xe70
   __netif_receive_skb_core.constprop.0+0xf7e/0x2b30

Fix this with a two-stage transaction. First allocate and stage all
buffers required for the packet, recycling all staged buffers with
xsk_buff_free() if any allocation fails. Only after this stage
succeeds, copy the data, reserve the RX descriptors, and release the
buffers in an error-free loop.
Comment 1 Keith Grant 2026-09-23 12:37:38 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90115.mbox