CVE-2026-46300

Description

In the Linux kernel, the following vulnerability has been resolved: net: skbuff: preserve shared-frag marker during coalescing skb_try_coalesce() can attach paged frags from @from to @to. If @from has SKBFL_SHARED_FRAG set, the resulting @to skb can contain the same externally-owned or page-cache-backed frags, but the shared-frag marker is currently lost. That breaks the invariant relied on by later in-place writers. In particular, ESP input checks skb_has_shared_frag() before deciding whether an uncloned nonlinear skb can skip skb_cow_data(). If TCP receive coalescing has moved shared frags into an unmarked skb, ESP can see skb_has_shared_frag() as false and decrypt in place over page-cache backed frags. Propagate SKBFL_SHARED_FRAG when skb_try_coalesce() transfers paged frags. The tailroom copy path does not need the marker because it copies bytes into @to's linear data rather than transferring frag descriptors.

References

• https://git.kernel.org/stable/c/2f2b16022a2e10ca7bccfb98db5ed2ec0f72641c
• https://git.kernel.org/stable/c/3599e6b3cc1ada96883d496a50a210d3afbb6987
• https://git.kernel.org/stable/c/3884358a9286b17f389a72b1426fc4547c23c111
• https://git.kernel.org/stable/c/3bd9e113d50034db99d7ef69fd8e5242d15e414a
• https://git.kernel.org/stable/c/760e1addc27ba1a7beb4a0a7e8b3e9ec49e7a34e