Affected: Linux

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

ixgbe: Fix panic during XDP_TX with > 64 CPUs

Commit 4fe815850bdc ("ixgbe: let the xdpdrv work with more than 64 cpus") adds support to allow XDP programs to run on systems with more than 64 CPUs by locking the XDP TX rings and indexing them using cpu % 64 (IXGBE_MAX_XDP_QS).

Upon trying this out patch on a system with more than 64 cores, the kernel paniced with an array-index-out-of-bounds at the return in ixgbe_determine_xdp_ring in ixgbe.h, which means ixgbe_determine_xdp_q_idx was just returning the cpu instead of cpu % IXGBE_MAX_XDP_QS. An example splat:

========================================================================== UBSAN: array-index-out-of-bounds in /var/lib/dkms/ixgbe/5.18.6+focal-1/build/src/ixgbe.h:1147:26 index 65 is out of range for type 'ixgbe_ring *[64]' ========================================================================== BUG: kernel NULL pointer dereference, address: 0000000000000058 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] SMP NOPTI CPU: 65 PID: 408 Comm: ksoftirqd/65 Tainted: G IOE 5.15.0-48-generic #54~20.04.1-Ubuntu Hardware name: Dell Inc. PowerEdge R640/0W23H8, BIOS 2.5.4 01/13/2020 RIP: 0010:ixgbe_xmit_xdp_ring+0x1b/0x1c0 [ixgbe] Code: 3b 52 d4 cf e9 42 f2 ff ff 66 0f 1f 44 00 00 0f 1f 44 00 00 55 b9 00 00 00 00 48 89 e5 41 57 41 56 41 55 41 54 53 48 83 ec 08 <44>…