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This > > >> leads to the following kernel panic due to a NULL pointer dereference. > > >> > > >> BUG: kernel NULL pointer dereference, address: 0000000000000000 > > >> #PF: supervisor read access in kernel mode > > >> #PF: error_code(0x0000) - not-present page > > >> PGD 0 P4D 0 > > >> Oops: Oops: 0000 [#1] SMP NOPTI > > >> CPU: 2 UID: 1 PID: 927 Comm: p4xsk.bin Not tainted 6.16.12+deb14-cloud-amd64 #1 PREEMPT(lazy) Debian 6.16.12-1 > > >> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 > > >> RIP: 0010:xsk_destruct_skb+0xd0/0x180 > > >> [...] > > >> Call Trace: > > >> > > >> ? napi_complete_done+0x7a/0x1a0 > > >> ip_rcv_core+0x1bb/0x340 > > >> ip_rcv+0x30/0x1f0 > > >> __netif_receive_skb_one_core+0x85/0xa0 > > >> process_backlog+0x87/0x130 > > >> __napi_poll+0x28/0x180 > > >> net_rx_action+0x339/0x420 > > >> handle_softirqs+0xdc/0x320 > > >> ? handle_edge_irq+0x90/0x1e0 > > >> do_softirq.part.0+0x3b/0x60 > > >> > > >> > > >> __local_bh_enable_ip+0x60/0x70 > > >> __dev_direct_xmit+0x14e/0x1f0 > > >> __xsk_generic_xmit+0x482/0xb70 > > >> ? __remove_hrtimer+0x41/0xa0 > > >> ? __xsk_generic_xmit+0x51/0xb70 > > >> ? _raw_spin_unlock_irqrestore+0xe/0x40 > > >> xsk_sendmsg+0xda/0x1c0 > > >> __sys_sendto+0x1ee/0x200 > > >> __x64_sys_sendto+0x24/0x30 > > >> do_syscall_64+0x84/0x2f0 > > >> ? __pfx_pollwake+0x10/0x10 > > >> ? __rseq_handle_notify_resume+0xad/0x4c0 > > >> ? restore_fpregs_from_fpstate+0x3c/0x90 > > >> ? switch_fpu_return+0x5b/0xe0 > > >> ? do_syscall_64+0x204/0x2f0 > > >> ? do_syscall_64+0x204/0x2f0 > > >> ? do_syscall_64+0x204/0x2f0 > > >> entry_SYSCALL_64_after_hwframe+0x76/0x7e > > >> > > >> [...] > > >> Kernel panic - not syncing: Fatal exception in interrupt > > >> Kernel Offset: 0x1c000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) > > >> > > >> Instead use the skb destructor_arg pointer along with pointer tagging. > > >> As pointers are always aligned to 8B, use the bottom bit to indicate > > >> whether this a single address or an allocated struct containing several > > >> addresses. > > >> > > >> Fixes: 30f241fcf52a ("xsk: Fix immature cq descriptor production") > > >> Closes: https://lore.kernel.org/netdev/0435b904-f44f-48f8-afb0-68868474bf1c@nop.hu/ > > >> Suggested-by: Jakub Kicinski > > >> Signed-off-by: Fernando Fernandez Mancera > > > > > > Reviewed-by: Jason Xing > > > > > > Could you also post a patch on top of net-next as it has diverged from > > > the net tree? > > > > > > > I think that is handled by maintainers when merging the branches. A > > repost would be wrong because linux-next.git and linux.git will have a > > different variant of the same commit.. > > But this patch cannot be applied cleanly in the net-next tree... What we care here is that it applies to net as that's a tree that this patch has been posted to. > > > > > Please, let me know if I am wrong here. > > I'm not quite sure either. > > Thanks, > Jason > > > > > Thanks, > > Fernando.