Linux vulnerability

What happened

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: fix dst corruption in same register operation For lshift and rshift, the shift operations are performed in a loop over 32-bit words. The loop calculates the shifted value and write it to dst, and then immediately reads from src to calculate the carry for the next iteration. Because src and dst could point to the same memory location, the carry is incorrectly calculated using the newly modified dst value instead of the original src value. Adding a temporary local variable to cache the original value before writing to dst and using it for the carry calculation solves the problem. In addition, partial overlap is rejected from control plane for all kind of operations including byteorder. This was tested with the following bytecode: table test_table ip flags 0 use 1 handle 1 ip test_table test_chain use 3 type filter hook input prio 0 policy accept packets 0 bytes 0 flags 1 ip test_table test_chain 2 [ immediate reg 1 0x44332211 0x88776655 ] [ bitwise reg 1 = ( reg 1 << 0x08000000 ) ] [ cmp eq reg 1 0x66443322 0x00887766 ] [ counter pkts 0 bytes 0 ] ip test_table test_chain 4 3 [ immediate reg 1 0x44332211 0x88776655 ] [ bitwise reg 1 = ( reg 1 << 0x08000000 ) ] [ cmp eq reg 1 0x55443322 0x00887766 ] [ counter pkts 21794 bytes 1917798 ]

Affected versions

Linux: 567d746b55bc66d3800c9ae91d50f0c5deb2fd93 through before b80ef316e978de2ef81d5bee9c19800b4cf96fb8 (git); 567d746b55bc66d3800c9ae91d50f0c5deb2fd93 through before 96bea2a7baac4a1137c188dc7610184487ab30a7 (git); 567d746b55bc66d3800c9ae91d50f0c5deb2fd93 through before a391afe74398b70107f111aa731eab608624949d (git); 567d746b55bc66d3800c9ae91d50f0c5deb2fd93 through before 18014147d3ee7831dce53fe65d7fc8d428b02552 (git); 5.6 Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.