Vulnerability details

In the Linux kernel, the following vulnerability has been resolved: ixgbevf: fix use-after-free in VEPA multicast source pruning ixgbevf_clean_rx_irq() prunes frames whose source MAC matches the VF's own address (VEPA multicast workaround) by freeing the skb and continuing to the next descriptor: dev_kfree_skb_irq(skb); continue; The skb pointer is declared outside the while loop and persists across iterations. Because the continue skips the "skb = NULL" reset at the bottom of the loop, the next iteration enters the "else if (skb)" path and calls ixgbevf_add_rx_frag() on the freed skb, dereferencing skb_shinfo(skb)->nr_frags - a use-after-free in NAPI softirq context. The sibling driver iavf already handles this correctly by nulling the pointer before continuing. Apply the same pattern here. I do not have ixgbevf hardware; the bug was found by static analysis (scan_drop_continue_loops.py + semgrep drop_continue_in_loop, multi-tool corroboration with the highest score in the scan). The UAF was confirmed under KASAN by loading a test module that reproduces the exact code pattern (alloc skb, kfree_skb, then read skb_shinfo(skb)->nr_frags): BUG: KASAN: slab-use-after-free in ixgbevf_uaf_test_init+0x100/0x1000 Read of size 8 at addr 000000006163ae78 by task insmod/30 freed 208-byte region [000000006163adc0, 000000006163ae90) QEMU emulates igb (82576) but not ixgbe (82599), and the igbvf VF driver does not include the VEPA source pruning path, so a full end-to-end reproduction with emulated hardware was not possible.

• https://git.kernel.org/stable/c/3d931ac62411a7e43b85dba5fe45e1a4a91bd5cb
• https://git.kernel.org/stable/c/6ef30384a50a50e4a484cddf341bc27de31aa3de
• https://git.kernel.org/stable/c/55b3e91d62b2f7a24109b2d7c9f4c66d2e3b1ec1
• https://git.kernel.org/stable/c/add70e2682c0ad3be2a5810bcf1bc13963ba4df9
• https://git.kernel.org/stable/c/a244395d8c563ed1bb26c3ef708db6aeeaa08084
• https://git.kernel.org/stable/c/dfef79e09ed2f5df975c98547f97f5d7f8982a24
• https://git.kernel.org/stable/c/e8768bcbe5cd30c4ea36a22022c9ffaa66903693
• https://git.kernel.org/stable/c/5d49b568c188dc77199d8d2b959c91da8cc27cf1