CVE-2026-89511: Undefined Security Weakness

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

qede: Fix NULL pointer dereference in TPA fragment processing

Under memory pressure, the qede driver encounters NULL pointer dereferences when processing TPA continuation fragments.

Commit 8a8633978b84 ("qede: Add build_skb() support.") accidentally dropped the assignment of tpa_info->buffer.data in qede_tpa_start().

When memory pressure causes an SKB allocation failure in qede_tpa_start(), the driver sets tpa_start_fail = true and attempts to recycle the physical page later in qede_tpa_end() via qede_reuse_page(). However, because buffer.data was left uninitialized (NULL), qede_reuse_page() pushes a "ghost" BD (valid DMA mapping but NULL data pointer) back into the active Rx ring.

The next time the hardware uses this ring slot, it passes a NULL page to qede_fill_frag_skb(), causing a kernel panic.

Example crash from production system: BUG: unable to handle kernel NULL pointer dereference at 0x8 RIP: qede_fill_frag_skb+0x96/0x430 [qede] Call Trace: qede_rx_int+0xb06/0x1de0 qede_poll+0x2f4/0x6c0 __napi_poll+0x2d/0x130

Fix the root cause by restoring the tpa_info->buffer.data assignment in qede_tpa_start(), ensuring valid pages are correctly tracked and recycled. Additionally, update the stale comment for struct qede_agg_info::buffer to reflect its current usage.