Bug 2492745 (CVE-2026-53235)

Summary: CVE-2026-53235 kernel: net: add pskb_may_pull() to skb_gro_receive_list()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's network Generic Receive Offload (GRO) handling. An attacker sending specially crafted network packets could trigger a bug in the `skb_gro_receive_list()` function. This occurs when the system attempts to process network data that is not in the expected linear memory area, leading to an incorrect buffer length calculation. The flaw can cause a system crash, resulting in a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-06-25 10:03:31 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net: add pskb_may_pull() to skb_gro_receive_list()

skb_gro_receive_list() calls skb_pull(skb, skb_gro_offset(skb)) without
first ensuring the data is in the linear area via pskb_may_pull(). When
the skb arrives via napi_gro_frags(), skb_headlen can be 0 (all data in
page fragments) while skb_gro_offset is non-zero (after IP+TCP header
parsing). The skb_pull() then decrements skb->len by skb_gro_offset
but skb->data_len stays unchanged, hitting BUG_ON(skb->len < skb->data_len)
in __skb_pull().

The UDP fraglist GRO path already contains this guard at
udp_offload.c:749. Adding it to skb_gro_receive_list() itself provides
centralized protection for all callers (TCP, UDP, and any future
protocols), and ensures the precondition of skb_pull() is satisfied
before it is called.

On pskb_may_pull() failure, set NAPI_GRO_CB(skb)->flush = 1 so the
skb is not held as a new GRO head and is instead delivered through the
normal receive path, matching the UDP handling.
Comment 1 TEJ RATHI 2026-06-26 08:33:48 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062509-CVE-2026-53235-a7f3@gregkh/T