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.

Fixes: 8a8633978b84 ("qede: Add build_skb() support.")
Cc: stable@vger.kernel.org
Signed-off-by: Vaibhav Nagare <vnagare@redhat.com>
Link: https://patch.msgid.link/20260818073309.2266072-1-vnagare@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions