CVE-2026-53134

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

netfilter: nft_fib: fix stale stack leak via the OIFNAME register

For NFTFIBRESULTOIFNAME the destination register is declared with len = IFNAMSIZ (four 32-bit registers), but on the lookup-fail, RTNLOCAL and oif-mismatch paths nftfib{4,6}eval() only writes one register via "*dest = 0". The remaining three registers are left as whatever was on the stack in nftdochain()'s struct nft_regs, and a downstream expression that loads the register span can leak that uninitialised kernel stack to userspace.

The NFTAFIBFPRESENT existence check has the same shape: it is only meaningful for NFTFIBRESULTOIF, yet it was accepted for any result type while the eval stores a single byte via nftregstore8(), leaving the rest of the declared span stale.

Fix both:

• replace the bare "*dest = 0" in the eval with nftfibstoreresult(), which strscpypad()s the whole IFNAMSIZ for OIFNAME (and is already used on the other early-return path), and

• restrict NFTAFIBFPRESENT to NFTFIBRESULTOIF and declare its destination as a single u8, so the marked span matches the one byte the eval writes.