fda85ce912
In the time between rxe_send has finished and skb destructor called, the QP's ref count might be 0, leading to a possible QP destruction. This will lead to a kernel panic when the destructor dereferences the QP. The operation of incrementing QP ref count at rxe_send and decrementing from skb destructor will prevent this crash. BUG: unable to handle kernel NULL pointer dereference at 000000000000072c IP: [<ffffffffa05df765>] rxe_skb_tx_dtor+0x15/0x50 [rdma_rxe] PGD 0 [16240.211178] Oops: 0002 [#1] SMP CPU: 3 PID: 0 Comm: swapper/3 Tainted: G OE 4.9.0-mlnx #1 Hardware name: Red Hat KVM, BIOS Bochs 01/01/2011 task: ffff88042d6b1480 task.stack: ffffc90001904000 RIP: 0010:[<ffffffffa05df765>] [<ffffffffa05df765>] rxe_skb_tx_dtor+0x15/0x50 [rdma_rxe] RSP: 0018:ffff88043fcc3df0 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff880429684700 RCX: ffff88042d248200 RDX: 00000000ffffffff RSI: 00000000fffffe01 RDI: ffff880429684700 RBP: ffff88043fcc3e00 R08: ffff88043fcda240 R09: 00000000ff2d1de6 R10: 0000000000000000 R11: 00000000f49cf6fe R12: ffff880429684700 R13: ffffffff81893f96 R14: ffffffff817d66f0 R15: ffff880427f74200 FS: 0000000000000000(0000) GS:ffff88043fcc0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000000072c CR3: 000000041d3df000 CR4: 00000000000006e0 Stack: ffffffff817b29cf ffff880429684700 ffff88043fcc3e18 ffffffff817b42c2 ffff880429684700 ffff88043fcc3e40 ffffffff817b4332 ffff880429684700 ffff880427f74238 ffff880427f74228 ffff88043fcc3e58 ffffffff81893f96 Call Trace: <IRQ> [16240.336345] [<ffffffff817b29cf>] ? skb_release_head_state+0x4f/0xb0 [<ffffffff817b42c2>] skb_release_all+0x12/0x30 [<ffffffff817b4332>] kfree_skb+0x32/0x90 [<ffffffff81893f96>] ndisc_error_report+0x36/0x40 [<ffffffff817d4de1>] neigh_invalidate+0x81/0xf0 [<ffffffff817d68f7>] neigh_timer_handler+0x207/0x2b0 [<ffffffff81109295>] call_timer_fn+0x35/0x120 [<ffffffff81109db7>] run_timer_softirq+0x1d7/0x460 [<ffffffff8106155e>] ? kvm_sched_clock_read+0x1e/0x30 [<ffffffff810366b9>] ? sched_clock+0x9/0x10 [<ffffffff810cfed2>] ? sched_clock_cpu+0x72/0xa0 [<ffffffff818dd537>] __do_softirq+0xd7/0x289 [<ffffffff810a6c95>] irq_exit+0xb5/0xc0 [<ffffffff818dd372>] smp_apic_timer_interrupt+0x42/0x50 [<ffffffff818dc682>] apic_timer_interrupt+0x82/0x90 <EOI> [16240.395776] [<ffffffff818da156>] ? native_safe_halt+0x6/0x10 [<ffffffff818d9e6e>] default_idle+0x1e/0xd0 [<ffffffff8103797f>] arch_cpu_idle+0xf/0x20 [<ffffffff818da2c5>] default_idle_call+0x35/0x40 [<ffffffff810e3eb5>] cpu_startup_entry+0x185/0x210 [<ffffffff81050433>] start_secondary+0x103/0x130 RIP [<ffffffffa05df765>] rxe_skb_tx_dtor+0x15/0x50 [rdma_rxe] Fixes: 8700e3e7c485 ("Soft RoCE driver") Signed-off-by: Yonatan Cohen <yonatanc@mellanox.com> Reviewed-by: Moni Shoua <monis@mellanox.com> Signed-off-by: Leon Romanovsky <leon@kernel.org> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Doug Ledford <dledford@redhat.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.