CVE-2026-23172

In the Linux kernel, the following vulnerability has been resolved:

net: wwan: t7xx: fix potential skb->frags overflow in RX path

When receiving data in the DPMAIF RX path, the t7xx_dpmaif_set_frag_to_skb() function adds page fragments to an skb without checking if the number of fragments has exceeded MAX_SKB_FRAGS. This could lead to a buffer overflow in skb_shinfo(skb)->frags[] array, corrupting adjacent memory and potentially causing kernel crashes or other undefined behavior.

This issue was identified through static code analysis by comparing with a similar vulnerability fixed in the mt76 driver commit b102f0c522cf (mt76: fix array overflow on receiving too many fragments for a packet).

The vulnerability could be triggered if the modem firmware sends packets with excessive fragments. While under normal protocol conditions (MTU 3080 bytes, BAT buffer 3584 bytes), a single packet should not require additional fragments, the kernel should not blindly trust firmware behavior. Malicious, buggy, or compromised firmware could potentially craft packets with more fragments than the kernel expects.

Fix this by adding a bounds check before calling skb_add_rx_frag() to ensure nr_frags does not exceed MAX_SKB_FRAGS.

The check must be performed before unmapping to avoid a page leak and double DMA unmap during device teardown.

Weakness

The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.

Affected Software

Potential Mitigations

• Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
• For example, glibc in Linux provides protection against free of invalid pointers.
• When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
• To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

References

• https://git.kernel.org/stable/c/2a0522f564acd34442652ea083091c329fa7c5d5
• https://git.kernel.org/stable/c/2c0fb0f60bc1545c52da61bc6bd4855c1e7814ba
• https://git.kernel.org/stable/c/af4b8577d0b388cc3d0039eb0cdd9ca5bbbc9276
• https://git.kernel.org/stable/c/f0813bcd2d9d97fdbdf2efb9532ab03ae92e99e6
• https://git.kernel.org/stable/c/f9747a7521a48afded5bff2faf1f2dcfff48c577