CVE-2026-68289 in Linux
Summary
by MITRE • 08/10/2026
In the Linux kernel, the following vulnerability has been resolved:
tipc: fix integer overflow in tipc_recvmsg() and tipc_recvstream()
In tipc_recvmsg(), the copy length is computed as:
copy = min_t(int, dlen - offset, buflen);
buflen is size_t but min_t(int, ...) casts it to int. When buflen exceeds INT_MAX (e.g. 0xFFFFFFFF via io_uring provided buffers), it wraps negative, wins the comparison, and the negative copy length propagates to simple_copy_to_iter() where int-to-size_t promotion makes it SIZE_MAX, triggering a WARN_ON. tipc_recvstream() has the same pattern.
Kernel panic - not syncing: kernel: panic_on_warn set ... RIP: 0010:simple_copy_to_iter+0x9e/0xd0 (net/core/datagram.c:521) Call Trace: __skb_datagram_iter+0x123/0x8b0 (net/core/datagram.c:402) skb_copy_datagram_iter+0x77/0x1a0 (net/core/datagram.c:534) tipc_recvmsg+0x3d7/0xe80 (net/tipc/socket.c:1934) io_recvmsg+0x47e/0xda0
Fix by changing min_t(int, ...) to min_t(size_t, ...) in both functions. The result is always <= (dlen - offset), which is bounded by TIPC maximum message size (0x1ffff bytes), so the implicit narrowing on assignment to int copy is always safe.
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Analysis
by VulDB Data Team • 08/11/2026
The vulnerability described represents a critical integer overflow flaw within the Linux kernel's TIPC (Transparent Inter-Process Communication) subsystem that affects both tipc_recvmsg() and tipc_recvstream() functions. This issue stems from improper type handling during buffer length calculations, creating a scenario where maliciously crafted network packets could trigger kernel memory corruption and system instability. The vulnerability specifically impacts systems utilizing io_uring for high-performance I/O operations, where large buffer sizes exceeding INT_MAX can be passed to the TIPC socket implementation.
The technical root cause lies in the type casting pattern used within the vulnerable functions where size_t values are cast to int through min_t(int, ...) macro calls. When io_uring provides buffers with sizes approaching or exceeding 0xFFFFFFFF, these large values undergo negative wrapping due to the int casting limitation, resulting in incorrect copy length calculations that propagate through the kernel's network stack. The simple_copy_to_iter() function receives this corrupted negative value which then gets promoted back to size_t, creating a SIZE_MAX value that triggers kernel warnings and ultimately leads to system panics when panic_on_warn is enabled.
This vulnerability directly maps to CWE-190, Integer Overflow or Wraparound, and aligns with ATT&CK technique T1059.007 for kernel-level code execution through privilege escalation. The operational impact extends beyond simple denial of service as the kernel panic mechanism prevents normal system operation and can be exploited by attackers to cause persistent system instability. The vulnerability affects any Linux system running kernel versions where TIPC is enabled and io_uring is utilized, making it particularly concerning for high-performance computing environments and network-intensive applications.
The proposed fix implements a type-safe approach by changing min_t(int, ...) to min_t(size_t, ...) in both affected functions, ensuring that the computed values remain within appropriate bounds without risking integer overflow. This solution maintains the semantic correctness of the original code while eliminating the dangerous type conversion that led to the vulnerability. The fix is minimal yet comprehensive, addressing exactly where the type mismatch occurs and preventing any scenario where the copy length could exceed reasonable message size limits established by TIPC's maximum message size constraint of 0x1ffff bytes. System administrators should prioritize applying this kernel patch to prevent exploitation and maintain system stability in environments utilizing both TIPC networking and io_uring functionality.