NULL Pointer Dereference

In the Linux kernel, the following vulnerability has been resolved: platform/x86: int3472: Check for adev == NULL Not all devices have an ACPI companion fwnode, so adev might be NULL. This can e.g. (theoretically) happen when a user manually binds one of the int3472 drivers to another i2c/platform device through sysfs. Add a check for adev not being set and return -ENODEV in that case to avoid a possible NULL pointer deref in skl_int3472_get_acpi_buffer().Show less

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: handle NULL sock pointer in l2cap_sock_alloc A NULL sock pointer is passed into l2cap_sock_alloc() when it is called from l2cap_sock_new_connection_cb() and the error handling paths should also be aware of it. Seemingly a more elegant solution would be to swap bt_sock_alloc() and l2cap_chan_create() calls since they are not interdependent to that moment but then l2cap_chan_create() adds the soon to be deallocated and still dummy-initialized channel to the global list accessible by many L2CAP paths. The channel would be removed from the list in short period of time but be a bit more straight-forward here and just check for NULL instead of changing the order of function calls. Found by Linux Verification Center (linuxtesting.org) with SVACE static analysis tool.Show less

In the Linux kernel, the following vulnerability has been resolved: firmware: qcom: scm: smc: Handle missing SCM device Commit ca61d6836e6f ("firmware: qcom: scm: fix a NULL-pointer dereference") makes it explicit that qcom_scm_get_tzmem_pool() can return NULL, therefore its users should handle this.Show less

In the Linux kernel, the following vulnerability has been resolved: media: vidtv: Fix a null-ptr-deref in vidtv_mux_stop_thread syzbot report a null-ptr-deref in vidtv_mux_stop_thread. [1] If dvb->mux is not initialized successfully by vidtv_mux_init() in the vidtv_start_streaming(), it will trigger null pointer dereference about mux in vidtv_mux_stop_thread(). Adjust the timing of streaming initialization and check it before stopping it. [1] KASAN: null-ptr-deref in range [0x0000000000000128-0x000000000000012f] CPU: 0 UID: 0 PID: 5842 Comm: syz-executor248 Not tainted 6.13.0-rc4-syzkaller-00012-g9b2ffa6148b1 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 RIP: 0010:vidtv_mux_stop_thread+0x26/0x80 drivers/media/test-drivers/vidtv/vidtv_mux.c:471 Code: 90 90 90 90 66 0f 1f 00 55 53 48 89 fb e8 82 2e c8 f9 48 8d bb 28 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 02 7e 3b 0f b6 ab 28 01 00 00 31 ff 89 ee e8 RSP: 0018:ffffc90003f2faa8 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff87cfb125 RDX: 0000000000000025 RSI: ffffffff87d120ce RDI: 0000000000000128 RBP: ffff888029b8d220 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000003 R12: ffff888029b8d188 R13: ffffffff8f590aa0 R14: ffffc9000581c5c8 R15: ffff888029a17710 FS: 00007f7eef5156c0(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7eef5e635c CR3: 0000000076ca6000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> vidtv_stop_streaming drivers/media/test-drivers/vidtv/vidtv_bridge.c:209 [inline] vidtv_stop_feed+0x151/0x250 drivers/media/test-drivers/vidtv/vidtv_bridge.c:252 dmx_section_feed_stop_filtering+0x90/0x160 drivers/media/dvb-core/dvb_demux.c:1000 dvb_dmxdev_feed_stop.isra.0+0x1ee/0x270 drivers/media/dvb-core/dmxdev.c:486 dvb_dmxdev_filter_stop+0x22a/0x3a0 drivers/media/dvb-core/dmxdev.c:559 dvb_dmxdev_filter_free drivers/media/dvb-core/dmxdev.c:840 [inline] dvb_demux_release+0x92/0x550 drivers/media/dvb-core/dmxdev.c:1246 __fput+0x3f8/0xb60 fs/file_table.c:450 task_work_run+0x14e/0x250 kernel/task_work.c:239 get_signal+0x1d3/0x2610 kernel/signal.c:2790 arch_do_signal_or_restart+0x90/0x7e0 arch/x86/kernel/signal.c:337 exit_to_user_mode_loop kernel/entry/common.c:111 [inline] exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline] __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline] syscall_exit_to_user_mode+0x150/0x2a0 kernel/entry/common.c:218 do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89 entry_SYSCALL_64_after_hwframe+0x77/0x7fShow less

In the Linux kernel, the following vulnerability has been resolved: scsi: mpi3mr: Fix possible crash when setting up bsg fails If bsg_setup_queue() fails, the bsg_queue is assigned a non-NULL value. Consequently, in mpi3mr_bsg_exit(), the condition "if(!mrioc->bsg_queue)" will not be satisfied, preventing execution from entering bsg_remove_queue(), which could lead to the following crash: BUG: kernel NULL pointer dereference, address: 000000000000041c Call Trace: <TASK> mpi3mr_bsg_exit+0x1f/0x50 [mpi3mr] mpi3mr_remove+0x6f/0x340 [mpi3mr] pci_device_remove+0x3f/0xb0 device_release_driver_internal+0x19d/0x220 unbind_store+0xa4/0xb0 kernfs_fop_write_iter+0x11f/0x200 vfs_write+0x1fc/0x3e0 ksys_write+0x67/0xe0 do_syscall_64+0x38/0x80 entry_SYSCALL_64_after_hwframe+0x78/0xe2Show less

In the Linux kernel, the following vulnerability has been resolved: xfrm: delete intermediate secpath entry in packet offload mode Packets handled by hardware have added secpath as a way to inform XFRM core code that this path was already handled. That secpath is not needed at all after policy is checked and it is removed later in the stack. However, in the case of IP forwarding is enabled (/proc/sys/net/ipv4/ip_forward), that secpath is not removed and packets which already were handled are reentered to the driver TX path with xfrm_offload set. The following kernel panic is observed in mlx5 in such case: mlx5_core 0000:04:00.0 enp4s0f0np0: Link up mlx5_core 0000:04:00.1 enp4s0f1np1: Link up Initializing XFRM netlink socket IPsec XFRM device driver BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page PGD 0 P4D 0 Oops: Oops: 0010 [#1] PREEMPT SMP CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.13.0-rc1-alex #3 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014 RIP: 0010:0x0 Code: Unable to access opcode bytes at 0xffffffffffffffd6. RSP: 0018:ffffb87380003800 EFLAGS: 00010206 RAX: ffff8df004e02600 RBX: ffffb873800038d8 RCX: 00000000ffff98cf RDX: ffff8df00733e108 RSI: ffff8df00521fb80 RDI: ffff8df001661f00 RBP: ffffb87380003850 R08: ffff8df013980000 R09: 0000000000000010 R10: 0000000000000002 R11: 0000000000000002 R12: ffff8df001661f00 R13: ffff8df00521fb80 R14: ffff8df00733e108 R15: ffff8df011faf04e FS: 0000000000000000(0000) GS:ffff8df46b800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 0000000106384000 CR4: 0000000000350ef0 Call Trace: <IRQ> ? show_regs+0x63/0x70 ? __die_body+0x20/0x60 ? __die+0x2b/0x40 ? page_fault_oops+0x15c/0x550 ? do_user_addr_fault+0x3ed/0x870 ? exc_page_fault+0x7f/0x190 ? asm_exc_page_fault+0x27/0x30 mlx5e_ipsec_handle_tx_skb+0xe7/0x2f0 [mlx5_core] mlx5e_xmit+0x58e/0x1980 [mlx5_core] ? __fib_lookup+0x6a/0xb0 dev_hard_start_xmit+0x82/0x1d0 sch_direct_xmit+0xfe/0x390 __dev_queue_xmit+0x6d8/0xee0 ? __fib_lookup+0x6a/0xb0 ? internal_add_timer+0x48/0x70 ? mod_timer+0xe2/0x2b0 neigh_resolve_output+0x115/0x1b0 __neigh_update+0x26a/0xc50 neigh_update+0x14/0x20 arp_process+0x2cb/0x8e0 ? __napi_build_skb+0x5e/0x70 arp_rcv+0x11e/0x1c0 ? dev_gro_receive+0x574/0x820 __netif_receive_skb_list_core+0x1cf/0x1f0 netif_receive_skb_list_internal+0x183/0x2a0 napi_complete_done+0x76/0x1c0 mlx5e_napi_poll+0x234/0x7a0 [mlx5_core] __napi_poll+0x2d/0x1f0 net_rx_action+0x1a6/0x370 ? atomic_notifier_call_chain+0x3b/0x50 ? irq_int_handler+0x15/0x20 [mlx5_core] handle_softirqs+0xb9/0x2f0 ? handle_irq_event+0x44/0x60 irq_exit_rcu+0xdb/0x100 common_interrupt+0x98/0xc0 </IRQ> <TASK> asm_common_interrupt+0x27/0x40 RIP: 0010:pv_native_safe_halt+0xb/0x10 Code: 09 c3 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 0f 22 0f 1f 84 00 00 00 00 00 90 eb 07 0f 00 2d 7f e9 36 00 fb 40 00 83 ff 07 77 21 89 ff ff 24 fd 88 3d a1 bd 0f 21 f8 RSP: 0018:ffffffffbe603de8 EFLAGS: 00000202 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000f92f46680 RDX: 0000000000000037 RSI: 00000000ffffffff RDI: 00000000000518d4 RBP: ffffffffbe603df0 R08: 000000cd42e4dffb R09: ffffffffbe603d70 R10: 0000004d80d62680 R11: 0000000000000001 R12: ffffffffbe60bf40 R13: 0000000000000000 R14: 0000000000000000 R15: ffffffffbe60aff8 ? default_idle+0x9/0x20 arch_cpu_idle+0x9/0x10 default_idle_call+0x29/0xf0 do_idle+0x1f2/0x240 cpu_startup_entry+0x2c/0x30 rest_init+0xe7/0x100 start_kernel+0x76b/0xb90 x86_64_start_reservations+0x18/0x30 x86_64_start_kernel+0xc0/0x110 ? setup_ghcb+0xe/0x130 common_startup_64+0x13e/0x141 </TASK> Modules linked in: esp4_offload esp4 xfrm_interface xfrm6_tunnel tunnel4 tunnel6 xfrm_user xfrm_algo binf ---truncated---Show less

In the Linux kernel, the following vulnerability has been resolved: powerpc/pseries/iommu: Don't unset window if it was never set On pSeries, when user attempts to use the same vfio container used by different iommu group, the spapr_tce_set_window() returns -EPERM and the subsequent cleanup leads to the below crash. Kernel attempted to read user page (308) - exploit attempt? BUG: Kernel NULL pointer dereference on read at 0x00000308 Faulting instruction address: 0xc0000000001ce358 Oops: Kernel access of bad area, sig: 11 [#1] NIP: c0000000001ce358 LR: c0000000001ce05c CTR: c00000000005add0 <snip> NIP [c0000000001ce358] spapr_tce_unset_window+0x3b8/0x510 LR [c0000000001ce05c] spapr_tce_unset_window+0xbc/0x510 Call Trace: spapr_tce_unset_window+0xbc/0x510 (unreliable) tce_iommu_attach_group+0x24c/0x340 [vfio_iommu_spapr_tce] vfio_container_attach_group+0xec/0x240 [vfio] vfio_group_fops_unl_ioctl+0x548/0xb00 [vfio] sys_ioctl+0x754/0x1580 system_call_exception+0x13c/0x330 system_call_vectored_common+0x15c/0x2ec <snip> --- interrupt: 3000 Fix this by having null check for the tbl passed to the spapr_tce_unset_window().Show less

In the Linux kernel, the following vulnerability has been resolved: wifi: mt76: mt7925: fix NULL deref check in mt7925_change_vif_links In mt7925_change_vif_links() devm_kzalloc() may return NULL but this returned value is not checked.Show less

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: btbcm: Fix NULL deref in btbcm_get_board_name() devm_kstrdup() can return a NULL pointer on failure,but this returned value in btbcm_get_board_name() is not checked. Add NULL check in btbcm_get_board_name(), to handle kernel NULL pointer dereference error.Show less

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: btrtl: check for NULL in btrtl_setup_realtek() If insert an USB dongle which chip is not maintained in ic_id_table, it will hit the NULL point accessed. Add a null point check to avoid the Kernel Oops.Show less

In the Linux kernel, the following vulnerability has been resolved: usb: xhci: Fix NULL pointer dereference on certain command aborts If a command is queued to the final usable TRB of a ring segment, the enqueue pointer is advanced to the subsequent link TRB and no further. If the command is later aborted, when the abort completion is handled the dequeue pointer is advanced to the first TRB of the next segment. If no further commands are queued, xhci_handle_stopped_cmd_ring() sees the ring pointers unequal and assumes that there is a pending command, so it calls xhci_mod_cmd_timer() which crashes if cur_cmd was NULL. Don't attempt timer setup if cur_cmd is NULL. The subsequent doorbell ring likely is unnecessary too, but it's harmless. Leave it alone. This is probably Bug 219532, but no confirmation has been received. The issue has been independently reproduced and confirmed fixed using a USB MCU programmed to NAK the Status stage of SET_ADDRESS forever. Everything continued working normally after several prevented crashes.Show less

In the Linux kernel, the following vulnerability has been resolved: media: imx-jpeg: Fix potential error pointer dereference in detach_pm() The proble is on the first line: if (jpeg->pd_dev[i] && !pm_runtime_suspended(jpeg->pd_dev[i])) If jpeg->pd_dev[i] is an error pointer, then passing it to pm_runtime_suspended() will lead to an Oops. The other conditions check for both error pointers and NULL, but it would be more clear to use the IS_ERR_OR_NULL() check for that.Show less

In the Linux kernel, the following vulnerability has been resolved: ata: libata-core: fix NULL pointer deref in ata_host_alloc_pinfo() In an unlikely (and probably wrong?) case that the 'ppi' parameter of ata_host_alloc_pinfo() points to an array starting with a NULL pointer, there's going to be a kernel oops as the 'pi' local variable won't get reassigned from the initial value of NULL. Initialize 'pi' instead to '&ata_dummy_port_info' to fix the possible kernel oops for good... Found by Linux Verification Center (linuxtesting.org) with the SVACE static analysis tool.Show less

In the Linux kernel, the following vulnerability has been resolved: ext4: add reserved GDT blocks check We capture a NULL pointer issue when resizing a corrupt ext4 image which is freshly clear resize_inode feature (not run e2fsck). It could be simply reproduced by following steps. The problem is because of the resize_inode feature was cleared, and it will convert the filesystem to meta_bg mode in ext4_resize_fs(), but the es->s_reserved_gdt_blocks was not reduced to zero, so could we mistakenly call reserve_backup_gdb() and passing an uninitialized resize_inode to it when adding new group descriptors. mkfs.ext4 /dev/sda 3G tune2fs -O ^resize_inode /dev/sda #forget to run requested e2fsck mount /dev/sda /mnt resize2fs /dev/sda 8G ======== BUG: kernel NULL pointer dereference, address: 0000000000000028 CPU: 19 PID: 3243 Comm: resize2fs Not tainted 5.18.0-rc7-00001-gfde086c5ebfd #748 ... RIP: 0010:ext4_flex_group_add+0xe08/0x2570 ... Call Trace: <TASK> ext4_resize_fs+0xbec/0x1660 __ext4_ioctl+0x1749/0x24e0 ext4_ioctl+0x12/0x20 __x64_sys_ioctl+0xa6/0x110 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f2dd739617b ======== The fix is simple, add a check in ext4_resize_begin() to make sure that the es->s_reserved_gdt_blocks is zero when the resize_inode feature is disabled.Show less

In the Linux kernel, the following vulnerability has been resolved: scsi: ibmvfc: Store vhost pointer during subcrq allocation Currently the back pointer from a queue to the vhost adapter isn't set until after subcrq interrupt registration. The value is available when a queue is first allocated and can/should be also set for primary and async queues as well as subcrqs. This fixes a crash observed during kexec/kdump on Power 9 with legacy XICS interrupt controller where a pending subcrq interrupt from the previous kernel can be replayed immediately upon IRQ registration resulting in dereference of a garbage backpointer in ibmvfc_interrupt_scsi(). Kernel attempted to read user page (58) - exploit attempt? (uid: 0) BUG: Kernel NULL pointer dereference on read at 0x00000058 Faulting instruction address: 0xc008000003216a08 Oops: Kernel access of bad area, sig: 11 [#1] ... NIP [c008000003216a08] ibmvfc_interrupt_scsi+0x40/0xb0 [ibmvfc] LR [c0000000082079e8] __handle_irq_event_percpu+0x98/0x270 Call Trace: [c000000047fa3d80] [c0000000123e6180] 0xc0000000123e6180 (unreliable) [c000000047fa3df0] [c0000000082079e8] __handle_irq_event_percpu+0x98/0x270 [c000000047fa3ea0] [c000000008207d18] handle_irq_event+0x98/0x188 [c000000047fa3ef0] [c00000000820f564] handle_fasteoi_irq+0xc4/0x310 [c000000047fa3f40] [c000000008205c60] generic_handle_irq+0x50/0x80 [c000000047fa3f60] [c000000008015c40] __do_irq+0x70/0x1a0 [c000000047fa3f90] [c000000008016d7c] __do_IRQ+0x9c/0x130 [c000000014622f60] [0000000020000000] 0x20000000 [c000000014622ff0] [c000000008016e50] do_IRQ+0x40/0xa0 [c000000014623020] [c000000008017044] replay_soft_interrupts+0x194/0x2f0 [c000000014623210] [c0000000080172a8] arch_local_irq_restore+0x108/0x170 [c000000014623240] [c000000008eb1008] _raw_spin_unlock_irqrestore+0x58/0xb0 [c000000014623270] [c00000000820b12c] __setup_irq+0x49c/0x9f0 [c000000014623310] [c00000000820b7c0] request_threaded_irq+0x140/0x230 [c000000014623380] [c008000003212a50] ibmvfc_register_scsi_channel+0x1e8/0x2f0 [ibmvfc] [c000000014623450] [c008000003213d1c] ibmvfc_init_sub_crqs+0xc4/0x1f0 [ibmvfc] [c0000000146234d0] [c0080000032145a8] ibmvfc_reset_crq+0x150/0x210 [ibmvfc] [c000000014623550] [c0080000032147c8] ibmvfc_init_crq+0x160/0x280 [ibmvfc] [c0000000146235f0] [c00800000321a9cc] ibmvfc_probe+0x2a4/0x530 [ibmvfc]Show less

In the Linux kernel, the following vulnerability has been resolved: filemap: Handle sibling entries in filemap_get_read_batch() If a read races with an invalidation followed by another read, it is possible for a folio to be replaced with a higher-order folio. If that happens, we'll see a sibling entry for the new folio in the next iteration of the loop. This manifests as a NULL pointer dereference while holding the RCU read lock. Handle this by simply returning. The next call will find the new folio and handle it correctly. The other ways of handling this rare race are more complex and it's just not worth it.Show less

In the Linux kernel, the following vulnerability has been resolved: net: phy: at803x: fix NULL pointer dereference on AR9331 PHY Latest kernel will explode on the PHY interrupt config, since it depends now on allocated priv. So, run probe to allocate priv to fix it. ar9331_switch ethernet.1:10 lan0 (uninitialized): PHY [!ahb!ethernet@1a000000!mdio!switch@10:00] driver [Qualcomm Atheros AR9331 built-in PHY] (irq=13) CPU 0 Unable to handle kernel paging request at virtual address 0000000a, epc == 8050e8a8, ra == 80504b34 ... Call Trace: [<8050e8a8>] at803x_config_intr+0x5c/0xd0 [<80504b34>] phy_request_interrupt+0xa8/0xd0 [<8050289c>] phylink_bringup_phy+0x2d8/0x3ac [<80502b68>] phylink_fwnode_phy_connect+0x118/0x130 [<8074d8ec>] dsa_slave_create+0x270/0x420 [<80743b04>] dsa_port_setup+0x12c/0x148 [<8074580c>] dsa_register_switch+0xaf0/0xcc0 [<80511344>] ar9331_sw_probe+0x370/0x388 [<8050cb78>] mdio_probe+0x44/0x70 [<804df300>] really_probe+0x200/0x424 [<804df7b4>] __driver_probe_device+0x290/0x298 [<804df810>] driver_probe_device+0x54/0xe4 [<804dfd50>] __device_attach_driver+0xe4/0x130 [<804dcb00>] bus_for_each_drv+0xb4/0xd8 [<804dfac4>] __device_attach+0x104/0x1a4 [<804ddd24>] bus_probe_device+0x48/0xc4 [<804deb44>] deferred_probe_work_func+0xf0/0x10c [<800a0ffc>] process_one_work+0x314/0x4d4 [<800a17fc>] worker_thread+0x2a4/0x354 [<800a9a54>] kthread+0x134/0x13c [<8006306c>] ret_from_kernel_thread+0x14/0x1c Same Issue would affect some other PHYs (QCA8081, QCA9561), so fix it too.Show less

In the Linux kernel, the following vulnerability has been resolved: afs: Fix dynamic root getattr The recent patch to make afs_getattr consult the server didn't account for the pseudo-inodes employed by the dynamic root-type afs superblock not having a volume or a server to access, and thus an oops occurs if such a directory is stat'd. Fix this by checking to see if the vnode->volume pointer actually points anywhere before following it in afs_getattr(). This can be tested by stat'ing a directory in /afs. It may be sufficient just to do "ls /afs" and the oops looks something like: BUG: kernel NULL pointer dereference, address: 0000000000000020 ... RIP: 0010:afs_getattr+0x8b/0x14b ... Call Trace: <TASK> vfs_statx+0x79/0xf5 vfs_fstatat+0x49/0x62Show less

In the Linux kernel, the following vulnerability has been resolved: tipc: move bc link creation back to tipc_node_create Shuang Li reported a NULL pointer dereference crash: [] BUG: kernel NULL pointer dereference, address: 0000000000000068 [] RIP: 0010:tipc_link_is_up+0x5/0x10 [tipc] [] Call Trace: [] <IRQ> [] tipc_bcast_rcv+0xa2/0x190 [tipc] [] tipc_node_bc_rcv+0x8b/0x200 [tipc] [] tipc_rcv+0x3af/0x5b0 [tipc] [] tipc_udp_recv+0xc7/0x1e0 [tipc] It was caused by the 'l' passed into tipc_bcast_rcv() is NULL. When it creates a node in tipc_node_check_dest(), after inserting the new node into hashtable in tipc_node_create(), it creates the bc link. However, there is a gap between this insert and bc link creation, a bc packet may come in and get the node from the hashtable then try to dereference its bc link, which is NULL. This patch is to fix it by moving the bc link creation before inserting into the hashtable. Note that for a preliminary node becoming "real", the bc link creation should also be called before it's rehashed, as we don't create it for preliminary nodes.Show less

In the Linux kernel, the following vulnerability has been resolved: xen/netback: avoid entering xenvif_rx_next_skb() with an empty rx queue xenvif_rx_next_skb() is expecting the rx queue not being empty, but in case the loop in xenvif_rx_action() is doing multiple iterations, the availability of another skb in the rx queue is not being checked. This can lead to crashes: [40072.537261] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [40072.537407] IP: xenvif_rx_skb+0x23/0x590 [xen_netback] [40072.537534] PGD 0 P4D 0 [40072.537644] Oops: 0000 [#1] SMP NOPTI [40072.537749] CPU: 0 PID: 12505 Comm: v1-c40247-q2-gu Not tainted 4.12.14-122.121-default #1 SLE12-SP5 [40072.537867] Hardware name: HP ProLiant DL580 Gen9/ProLiant DL580 Gen9, BIOS U17 11/23/2021 [40072.537999] task: ffff880433b38100 task.stack: ffffc90043d40000 [40072.538112] RIP: e030:xenvif_rx_skb+0x23/0x590 [xen_netback] [40072.538217] RSP: e02b:ffffc90043d43de0 EFLAGS: 00010246 [40072.538319] RAX: 0000000000000000 RBX: ffffc90043cd7cd0 RCX: 00000000000000f7 [40072.538430] RDX: 0000000000000000 RSI: 0000000000000006 RDI: ffffc90043d43df8 [40072.538531] RBP: 000000000000003f R08: 000077ff80000000 R09: 0000000000000008 [40072.538644] R10: 0000000000007ff0 R11: 00000000000008f6 R12: ffffc90043ce2708 [40072.538745] R13: 0000000000000000 R14: ffffc90043d43ed0 R15: ffff88043ea748c0 [40072.538861] FS: 0000000000000000(0000) GS:ffff880484600000(0000) knlGS:0000000000000000 [40072.538988] CS: e033 DS: 0000 ES: 0000 CR0: 0000000080050033 [40072.539088] CR2: 0000000000000080 CR3: 0000000407ac8000 CR4: 0000000000040660 [40072.539211] Call Trace: [40072.539319] xenvif_rx_action+0x71/0x90 [xen_netback] [40072.539429] xenvif_kthread_guest_rx+0x14a/0x29c [xen_netback] Fix that by stopping the loop in case the rx queue becomes empty.Show less