Bug 2467025 (CVE-2026-43098)

Summary: CVE-2026-43098 kernel: nfc: s3fwrn5: allocate rx skb before consuming bytes
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Near Field Communication (NFC) subsystem, specifically within the s3fwrn5 driver. This vulnerability occurs when the driver attempts to consume bytes into a receive buffer (recv_skb) without ensuring a new buffer is allocated if the previous one was delivered. If the allocation of a new buffer fails, the `recv_skb` pointer can become NULL, leading to a NULL dereference during subsequent operations. A local attacker could exploit this memory corruption vulnerability to cause a system crash, resulting in a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-05-06 10:03:45 UTC 
In the Linux kernel, the following vulnerability has been resolved:

nfc: s3fwrn5: allocate rx skb before consuming bytes

s3fwrn82_uart_read() reports the number of accepted bytes to the serdev
core. The current code consumes bytes into recv_skb and may already
deliver a complete frame before allocating a fresh receive buffer.

If that alloc_skb() fails, the callback returns 0 even though it has
already consumed bytes, and it leaves recv_skb as NULL for the next
receive callback. That breaks the receive_buf() accounting contract and
can also lead to a NULL dereference on the next skb_put_u8().

Allocate the receive skb lazily before consuming the next byte instead.
If allocation fails, return the number of bytes already accepted.
Comment 1 Alexander B 2026-05-06 13:04:02 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026050620-CVE-2026-43098-960f@gregkh/T