Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: drm: mxsfb: Fix NULL pointer dereference crash on unload The mxsfb->crtc.funcs may already be NULL when unloading the driver, in which case calling mxsfb_irq_disable() via drm_irq_uninstall() from mxsfb_unload() leads to NULL pointer dereference. Since all we care about is masking the IRQ and mxsfb->base is still valid, just use that to clear and mask the IRQ.Show less

In the Linux kernel, the following vulnerability has been resolved: mm, slub: fix potential use-after-free in slab_debugfs_fops When sysfs_slab_add failed, we shouldn't call debugfs_slab_add() for s because s will be freed soon. And slab_debugfs_fops will use s later leading to a use-after-free.Show less

In the Linux kernel, the following vulnerability has been resolved: isdn: mISDN: Fix sleeping function called from invalid context The driver can call card->isac.release() function from an atomic context. Fix this by calling this function after releasing the lock. The following log reveals it: [ 44.168226 ] BUG: sleeping function called from invalid context at kernel/workqueue.c:3018 [ 44.168941 ] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 5475, name: modprobe [ 44.169574 ] INFO: lockdep is turned off. [ 44.169899 ] irq event stamp: 0 [ 44.170160 ] hardirqs last enabled at (0): [<0000000000000000>] 0x0 [ 44.170627 ] hardirqs last disabled at (0): [<ffffffff814209ed>] copy_process+0x132d/0x3e00 [ 44.171240 ] softirqs last enabled at (0): [<ffffffff81420a1a>] copy_process+0x135a/0x3e00 [ 44.171852 ] softirqs last disabled at (0): [<0000000000000000>] 0x0 [ 44.172318 ] Preemption disabled at: [ 44.172320 ] [<ffffffffa009b0a9>] nj_release+0x69/0x500 [netjet] [ 44.174441 ] Call Trace: [ 44.174630 ] dump_stack_lvl+0xa8/0xd1 [ 44.174912 ] dump_stack+0x15/0x17 [ 44.175166 ] ___might_sleep+0x3a2/0x510 [ 44.175459 ] ? nj_release+0x69/0x500 [netjet] [ 44.175791 ] __might_sleep+0x82/0xe0 [ 44.176063 ] ? start_flush_work+0x20/0x7b0 [ 44.176375 ] start_flush_work+0x33/0x7b0 [ 44.176672 ] ? trace_irq_enable_rcuidle+0x85/0x170 [ 44.177034 ] ? kasan_quarantine_put+0xaa/0x1f0 [ 44.177372 ] ? kasan_quarantine_put+0xaa/0x1f0 [ 44.177711 ] __flush_work+0x11a/0x1a0 [ 44.177991 ] ? flush_work+0x20/0x20 [ 44.178257 ] ? lock_release+0x13c/0x8f0 [ 44.178550 ] ? __kasan_check_write+0x14/0x20 [ 44.178872 ] ? do_raw_spin_lock+0x148/0x360 [ 44.179187 ] ? read_lock_is_recursive+0x20/0x20 [ 44.179530 ] ? __kasan_check_read+0x11/0x20 [ 44.179846 ] ? do_raw_spin_unlock+0x55/0x900 [ 44.180168 ] ? ____kasan_slab_free+0x116/0x140 [ 44.180505 ] ? _raw_spin_unlock_irqrestore+0x41/0x60 [ 44.180878 ] ? skb_queue_purge+0x1a3/0x1c0 [ 44.181189 ] ? kfree+0x13e/0x290 [ 44.181438 ] flush_work+0x17/0x20 [ 44.181695 ] mISDN_freedchannel+0xe8/0x100 [ 44.182006 ] isac_release+0x210/0x260 [mISDNipac] [ 44.182366 ] nj_release+0xf6/0x500 [netjet] [ 44.182685 ] nj_remove+0x48/0x70 [netjet] [ 44.182989 ] pci_device_remove+0xa9/0x250Show less

In the Linux kernel, the following vulnerability has been resolved: kunit: fix reference count leak in kfree_at_end The reference counting issue happens in the normal path of kfree_at_end(). When kunit_alloc_and_get_resource() is invoked, the function forgets to handle the returned resource object, whose refcount increased inside, causing a refcount leak. Fix this issue by calling kunit_alloc_resource() instead of kunit_alloc_and_get_resource(). Fixed the following when applying: Shuah Khan <skhan@linuxfoundation.org> CHECK: Alignment should match open parenthesis + kunit_alloc_resource(test, NULL, kfree_res_free, GFP_KERNEL, (void *)to_free);Show less

In the Linux kernel, the following vulnerability has been resolved: mm, slub: fix potential memoryleak in kmem_cache_open() In error path, the random_seq of slub cache might be leaked. Fix this by using __kmem_cache_release() to release all the relevant resources.Show less

In the Linux kernel, the following vulnerability has been resolved: KVM: PPC: Book3S HV: Fix stack handling in idle_kvm_start_guest() In commit 10d91611f426 ("powerpc/64s: Reimplement book3s idle code in C") kvm_start_guest() became idle_kvm_start_guest(). The old code allocated a stack frame on the emergency stack, but didn't use the frame to store anything, and also didn't store anything in its caller's frame. idle_kvm_start_guest() on the other hand is written more like a normal C function, it creates a frame on entry, and also stores CR/LR into its callers frame (per the ABI). The problem is that there is no caller frame on the emergency stack. The emergency stack for a given CPU is allocated with: paca_ptrs[i]->emergency_sp = alloc_stack(limit, i) + THREAD_SIZE; So emergency_sp actually points to the first address above the emergency stack allocation for a given CPU, we must not store above it without first decrementing it to create a frame. This is different to the regular kernel stack, paca->kstack, which is initialised to point at an initial frame that is ready to use. idle_kvm_start_guest() stores the backchain, CR and LR all of which write outside the allocation for the emergency stack. It then creates a stack frame and saves the non-volatile registers. Unfortunately the frame it creates is not large enough to fit the non-volatiles, and so the saving of the non-volatile registers also writes outside the emergency stack allocation. The end result is that we corrupt whatever is at 0-24 bytes, and 112-248 bytes above the emergency stack allocation. In practice this has gone unnoticed because the memory immediately above the emergency stack happens to be used for other stack allocations, either another CPUs mc_emergency_sp or an IRQ stack. See the order of calls to irqstack_early_init() and emergency_stack_init(). The low addresses of another stack are the top of that stack, and so are only used if that stack is under extreme pressue, which essentially never happens in practice - and if it did there's a high likelyhood we'd crash due to that stack overflowing. Still, we shouldn't be corrupting someone else's stack, and it is purely luck that we aren't corrupting something else. To fix it we save CR/LR into the caller's frame using the existing r1 on entry, we then create a SWITCH_FRAME_SIZE frame (which has space for pt_regs) on the emergency stack with the backchain pointing to the existing stack, and then finally we switch to the new frame on the emergency stack.Show less

In the Linux kernel, the following vulnerability has been resolved: audit: fix possible null-pointer dereference in audit_filter_rules Fix possible null-pointer dereference in audit_filter_rules. audit_filter_rules() error: we previously assumed 'ctx' could be nullShow less

In the Linux kernel, the following vulnerability has been resolved: mm/secretmem: fix NULL page->mapping dereference in page_is_secretmem() Check for a NULL page->mapping before dereferencing the mapping in page_is_secretmem(), as the page's mapping can be nullified while gup() is running, e.g. by reclaim or truncation. BUG: kernel NULL pointer dereference, address: 0000000000000068 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 6 PID: 4173897 Comm: CPU 3/KVM Tainted: G W RIP: 0010:internal_get_user_pages_fast+0x621/0x9d0 Code: <48> 81 7a 68 80 08 04 bc 0f 85 21 ff ff 8 89 c7 be RSP: 0018:ffffaa90087679b0 EFLAGS: 00010046 RAX: ffffe3f37905b900 RBX: 00007f2dd561e000 RCX: ffffe3f37905b934 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffe3f37905b900 ... CR2: 0000000000000068 CR3: 00000004c5898003 CR4: 00000000001726e0 Call Trace: get_user_pages_fast_only+0x13/0x20 hva_to_pfn+0xa9/0x3e0 try_async_pf+0xa1/0x270 direct_page_fault+0x113/0xad0 kvm_mmu_page_fault+0x69/0x680 vmx_handle_exit+0xe1/0x5d0 kvm_arch_vcpu_ioctl_run+0xd81/0x1c70 kvm_vcpu_ioctl+0x267/0x670 __x64_sys_ioctl+0x83/0xa0 do_syscall_64+0x56/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xaeShow less

In the Linux kernel, the following vulnerability has been resolved: mm/mempolicy: do not allow illegal MPOL_F_NUMA_BALANCING | MPOL_LOCAL in mbind() syzbot reported access to unitialized memory in mbind() [1] Issue came with commit bda420b98505 ("numa balancing: migrate on fault among multiple bound nodes") This commit added a new bit in MPOL_MODE_FLAGS, but only checked valid combination (MPOL_F_NUMA_BALANCING can only be used with MPOL_BIND) in do_set_mempolicy() This patch moves the check in sanitize_mpol_flags() so that it is also used by mbind() [1] BUG: KMSAN: uninit-value in __mpol_equal+0x567/0x590 mm/mempolicy.c:2260 __mpol_equal+0x567/0x590 mm/mempolicy.c:2260 mpol_equal include/linux/mempolicy.h:105 [inline] vma_merge+0x4a1/0x1e60 mm/mmap.c:1190 mbind_range+0xcc8/0x1e80 mm/mempolicy.c:811 do_mbind+0xf42/0x15f0 mm/mempolicy.c:1333 kernel_mbind mm/mempolicy.c:1483 [inline] __do_sys_mbind mm/mempolicy.c:1490 [inline] __se_sys_mbind+0x437/0xb80 mm/mempolicy.c:1486 __x64_sys_mbind+0x19d/0x200 mm/mempolicy.c:1486 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x44/0xae Uninit was created at: slab_alloc_node mm/slub.c:3221 [inline] slab_alloc mm/slub.c:3230 [inline] kmem_cache_alloc+0x751/0xff0 mm/slub.c:3235 mpol_new mm/mempolicy.c:293 [inline] do_mbind+0x912/0x15f0 mm/mempolicy.c:1289 kernel_mbind mm/mempolicy.c:1483 [inline] __do_sys_mbind mm/mempolicy.c:1490 [inline] __se_sys_mbind+0x437/0xb80 mm/mempolicy.c:1486 __x64_sys_mbind+0x19d/0x200 mm/mempolicy.c:1486 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x44/0xae ===================================================== Kernel panic - not syncing: panic_on_kmsan set ... CPU: 0 PID: 15049 Comm: syz-executor.0 Tainted: G B 5.15.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1ff/0x28e lib/dump_stack.c:106 dump_stack+0x25/0x28 lib/dump_stack.c:113 panic+0x44f/0xdeb kernel/panic.c:232 kmsan_report+0x2ee/0x300 mm/kmsan/report.c:186 __msan_warning+0xd7/0x150 mm/kmsan/instrumentation.c:208 __mpol_equal+0x567/0x590 mm/mempolicy.c:2260 mpol_equal include/linux/mempolicy.h:105 [inline] vma_merge+0x4a1/0x1e60 mm/mmap.c:1190 mbind_range+0xcc8/0x1e80 mm/mempolicy.c:811 do_mbind+0xf42/0x15f0 mm/mempolicy.c:1333 kernel_mbind mm/mempolicy.c:1483 [inline] __do_sys_mbind mm/mempolicy.c:1490 [inline] __se_sys_mbind+0x437/0xb80 mm/mempolicy.c:1486 __x64_sys_mbind+0x19d/0x200 mm/mempolicy.c:1486 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x44/0xaeShow less

In the Linux kernel, the following vulnerability has been resolved: userfaultfd: fix a race between writeprotect and exit_mmap() A race is possible when a process exits, its VMAs are removed by exit_mmap() and at the same time userfaultfd_writeprotect() is called. The race was detected by KASAN on a development kernel, but it appears to be possible on vanilla kernels as well. Use mmget_not_zero() to prevent the race as done in other userfaultfd operations.Show less

In the Linux kernel, the following vulnerability has been resolved: ocfs2: fix data corruption after conversion from inline format Commit 6dbf7bb55598 ("fs: Don't invalidate page buffers in block_write_full_page()") uncovered a latent bug in ocfs2 conversion from inline inode format to a normal inode format. The code in ocfs2_convert_inline_data_to_extents() attempts to zero out the whole cluster allocated for file data by grabbing, zeroing, and dirtying all pages covering this cluster. However these pages are beyond i_size, thus writeback code generally ignores these dirty pages and no blocks were ever actually zeroed on the disk. This oversight was fixed by commit 693c241a5f6a ("ocfs2: No need to zero pages past i_size.") for standard ocfs2 write path, inline conversion path was apparently forgotten; the commit log also has a reasoning why the zeroing actually is not needed. After commit 6dbf7bb55598, things became worse as writeback code stopped invalidating buffers on pages beyond i_size and thus these pages end up with clean PageDirty bit but with buffers attached to these pages being still dirty. So when a file is converted from inline format, then writeback triggers, and then the file is grown so that these pages become valid, the invalid dirtiness state is preserved, mark_buffer_dirty() does nothing on these pages (buffers are already dirty) but page is never written back because it is clean. So data written to these pages is lost once pages are reclaimed. Simple reproducer for the problem is: xfs_io -f -c "pwrite 0 2000" -c "pwrite 2000 2000" -c "fsync" \ -c "pwrite 4000 2000" ocfs2_file After unmounting and mounting the fs again, you can observe that end of 'ocfs2_file' has lost its contents. Fix the problem by not doing the pointless zeroing during conversion from inline format similarly as in the standard write path. [akpm@linux-foundation.org: fix whitespace, per Joseph]Show less

In the Linux kernel, the following vulnerability has been resolved: can: j1939: j1939_netdev_start(): fix UAF for rx_kref of j1939_priv It will trigger UAF for rx_kref of j1939_priv as following. cpu0 cpu1 j1939_sk_bind(socket0, ndev0, ...) j1939_netdev_start j1939_sk_bind(socket1, ndev0, ...) j1939_netdev_start j1939_priv_set j1939_priv_get_by_ndev_locked j1939_jsk_add ..... j1939_netdev_stop kref_put_lock(&priv->rx_kref, ...) kref_get(&priv->rx_kref, ...) REFCOUNT_WARN("addition on 0;...") ==================================================== refcount_t: addition on 0; use-after-free. WARNING: CPU: 1 PID: 20874 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0 RIP: 0010:refcount_warn_saturate+0x169/0x1e0 Call Trace: j1939_netdev_start+0x68b/0x920 j1939_sk_bind+0x426/0xeb0 ? security_socket_bind+0x83/0xb0 The rx_kref's kref_get() and kref_put() should use j1939_netdev_lock to protect.Show less

In the Linux kernel, the following vulnerability has been resolved: ocfs2: mount fails with buffer overflow in strlen Starting with kernel 5.11 built with CONFIG_FORTIFY_SOURCE mouting an ocfs2 filesystem with either o2cb or pcmk cluster stack fails with the trace below. Problem seems to be that strings for cluster stack and cluster name are not guaranteed to be null terminated in the disk representation, while strlcpy assumes that the source string is always null terminated. This causes a read outside of the source string triggering the buffer overflow detection. detected buffer overflow in strlen ------------[ cut here ]------------ kernel BUG at lib/string.c:1149! invalid opcode: 0000 [#1] SMP PTI CPU: 1 PID: 910 Comm: mount.ocfs2 Not tainted 5.14.0-1-amd64 #1 Debian 5.14.6-2 RIP: 0010:fortify_panic+0xf/0x11 ... Call Trace: ocfs2_initialize_super.isra.0.cold+0xc/0x18 [ocfs2] ocfs2_fill_super+0x359/0x19b0 [ocfs2] mount_bdev+0x185/0x1b0 legacy_get_tree+0x27/0x40 vfs_get_tree+0x25/0xb0 path_mount+0x454/0xa20 __x64_sys_mount+0x103/0x140 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xaeShow less

In the Linux kernel, the following vulnerability has been resolved: can: isotp: isotp_sendmsg(): add result check for wait_event_interruptible() Using wait_event_interruptible() to wait for complete transmission, but do not check the result of wait_event_interruptible() which can be interrupted. It will result in TX buffer has multiple accessors and the later process interferes with the previous process. Following is one of the problems reported by syzbot. ============================================================= WARNING: CPU: 0 PID: 0 at net/can/isotp.c:840 isotp_tx_timer_handler+0x2e0/0x4c0 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.13.0-rc7+ #68 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014 RIP: 0010:isotp_tx_timer_handler+0x2e0/0x4c0 Call Trace: <IRQ> ? isotp_setsockopt+0x390/0x390 __hrtimer_run_queues+0xb8/0x610 hrtimer_run_softirq+0x91/0xd0 ? rcu_read_lock_sched_held+0x4d/0x80 __do_softirq+0xe8/0x553 irq_exit_rcu+0xf8/0x100 sysvec_apic_timer_interrupt+0x9e/0xc0 </IRQ> asm_sysvec_apic_timer_interrupt+0x12/0x20 Add result check for wait_event_interruptible() in isotp_sendmsg() to avoid multiple accessers for tx buffer.Show less

In the Linux kernel, the following vulnerability has been resolved: can: peak_pci: peak_pci_remove(): fix UAF When remove the module peek_pci, referencing 'chan' again after releasing 'dev' will cause UAF. Fix this by releasing 'dev' later. The following log reveals it: [ 35.961814 ] BUG: KASAN: use-after-free in peak_pci_remove+0x16f/0x270 [peak_pci] [ 35.963414 ] Read of size 8 at addr ffff888136998ee8 by task modprobe/5537 [ 35.965513 ] Call Trace: [ 35.965718 ] dump_stack_lvl+0xa8/0xd1 [ 35.966028 ] print_address_description+0x87/0x3b0 [ 35.966420 ] kasan_report+0x172/0x1c0 [ 35.966725 ] ? peak_pci_remove+0x16f/0x270 [peak_pci] [ 35.967137 ] ? trace_irq_enable_rcuidle+0x10/0x170 [ 35.967529 ] ? peak_pci_remove+0x16f/0x270 [peak_pci] [ 35.967945 ] __asan_report_load8_noabort+0x14/0x20 [ 35.968346 ] peak_pci_remove+0x16f/0x270 [peak_pci] [ 35.968752 ] pci_device_remove+0xa9/0x250Show less

In the Linux kernel, the following vulnerability has been resolved: ptp: Fix possible memory leak in ptp_clock_register() I got memory leak as follows when doing fault injection test: unreferenced object 0xffff88800906c618 (size 8): comm "i2c-idt82p33931", pid 4421, jiffies 4294948083 (age 13.188s) hex dump (first 8 bytes): 70 74 70 30 00 00 00 00 ptp0.... backtrace: [<00000000312ed458>] __kmalloc_track_caller+0x19f/0x3a0 [<0000000079f6e2ff>] kvasprintf+0xb5/0x150 [<0000000026aae54f>] kvasprintf_const+0x60/0x190 [<00000000f323a5f7>] kobject_set_name_vargs+0x56/0x150 [<000000004e35abdd>] dev_set_name+0xc0/0x100 [<00000000f20cfe25>] ptp_clock_register+0x9f4/0xd30 [ptp] [<000000008bb9f0de>] idt82p33_probe.cold+0x8b6/0x1561 [ptp_idt82p33] When posix_clock_register() returns an error, the name allocated in dev_set_name() will be leaked, the put_device() should be used to give up the device reference, then the name will be freed in kobject_cleanup() and other memory will be freed in ptp_clock_release().Show less

In the Linux kernel, the following vulnerability has been resolved: powerpc/smp: do not decrement idle task preempt count in CPU offline With PREEMPT_COUNT=y, when a CPU is offlined and then onlined again, we get: BUG: scheduling while atomic: swapper/1/0/0x00000000 no locks held by swapper/1/0. CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.15.0-rc2+ #100 Call Trace: dump_stack_lvl+0xac/0x108 __schedule_bug+0xac/0xe0 __schedule+0xcf8/0x10d0 schedule_idle+0x3c/0x70 do_idle+0x2d8/0x4a0 cpu_startup_entry+0x38/0x40 start_secondary+0x2ec/0x3a0 start_secondary_prolog+0x10/0x14 This is because powerpc's arch_cpu_idle_dead() decrements the idle task's preempt count, for reasons explained in commit a7c2bb8279d2 ("powerpc: Re-enable preemption before cpu_die()"), specifically "start_secondary() expects a preempt_count() of 0." However, since commit 2c669ef6979c ("powerpc/preempt: Don't touch the idle task's preempt_count during hotplug") and commit f1a0a376ca0c ("sched/core: Initialize the idle task with preemption disabled"), that justification no longer holds. The idle task isn't supposed to re-enable preemption, so remove the vestigial preempt_enable() from the CPU offline path. Tested with pseries and powernv in qemu, and pseries on PowerVM.Show less

In the Linux kernel, the following vulnerability has been resolved: ice: Avoid crash from unnecessary IDA free In the remove path, there is an attempt to free the aux_idx IDA whether it was allocated or not. This can potentially cause a crash when unloading the driver on systems that do not initialize support for RDMA. But, this free cannot be gated by the status bit for RDMA, since it is allocated if the driver detects support for RDMA at probe time, but the driver can enter into a state where RDMA is not supported after the IDA has been allocated at probe time and this would lead to a memory leak. Initialize aux_idx to an invalid value and check for a valid value when unloading to determine if an IDA free is necessary.Show less

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: skip netdev events generated on netns removal syzbot reported following (harmless) WARN: WARNING: CPU: 1 PID: 2648 at net/netfilter/core.c:468 nft_netdev_unregister_hooks net/netfilter/nf_tables_api.c:230 [inline] nf_tables_unregister_hook include/net/netfilter/nf_tables.h:1090 [inline] __nft_release_basechain+0x138/0x640 net/netfilter/nf_tables_api.c:9524 nft_netdev_event net/netfilter/nft_chain_filter.c:351 [inline] nf_tables_netdev_event+0x521/0x8a0 net/netfilter/nft_chain_filter.c:382 reproducer: unshare -n bash -c 'ip link add br0 type bridge; nft add table netdev t ; \ nft add chain netdev t ingress \{ type filter hook ingress device "br0" \ priority 0\; policy drop\; \}' Problem is that when netns device exit hooks create the UNREGISTER event, the .pre_exit hook for nf_tables core has already removed the base hook. Notifier attempts to do this again. The need to do base hook unregister unconditionally was needed in the past, because notifier was last stage where reg->dev dereference was safe. Now that nf_tables does the hook removal in .pre_exit, this isn't needed anymore.Show less

In the Linux kernel, the following vulnerability has been resolved: netfilter: xt_IDLETIMER: fix panic that occurs when timer_type has garbage value Currently, when the rule related to IDLETIMER is added, idletimer_tg timer structure is initialized by kmalloc on executing idletimer_tg_create function. However, in this process timer->timer_type is not defined to a specific value. Thus, timer->timer_type has garbage value and it occurs kernel panic. So, this commit fixes the panic by initializing timer->timer_type using kzalloc instead of kmalloc. Test commands: # iptables -A OUTPUT -j IDLETIMER --timeout 1 --label test $ cat /sys/class/xt_idletimer/timers/test Killed Splat looks like: BUG: KASAN: user-memory-access in alarm_expires_remaining+0x49/0x70 Read of size 8 at addr 0000002e8c7bc4c8 by task cat/917 CPU: 12 PID: 917 Comm: cat Not tainted 5.14.0+ #3 79940a339f71eb14fc81aee1757a20d5bf13eb0e Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Call Trace: dump_stack_lvl+0x6e/0x9c kasan_report.cold+0x112/0x117 ? alarm_expires_remaining+0x49/0x70 __asan_load8+0x86/0xb0 alarm_expires_remaining+0x49/0x70 idletimer_tg_show+0xe5/0x19b [xt_IDLETIMER 11219304af9316a21bee5ba9d58f76a6b9bccc6d] dev_attr_show+0x3c/0x60 sysfs_kf_seq_show+0x11d/0x1f0 ? device_remove_bin_file+0x20/0x20 kernfs_seq_show+0xa4/0xb0 seq_read_iter+0x29c/0x750 kernfs_fop_read_iter+0x25a/0x2c0 ? __fsnotify_parent+0x3d1/0x570 ? iov_iter_init+0x70/0x90 new_sync_read+0x2a7/0x3d0 ? __x64_sys_llseek+0x230/0x230 ? rw_verify_area+0x81/0x150 vfs_read+0x17b/0x240 ksys_read+0xd9/0x180 ? vfs_write+0x460/0x460 ? do_syscall_64+0x16/0xc0 ? lockdep_hardirqs_on+0x79/0x120 __x64_sys_read+0x43/0x50 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f0cdc819142 Code: c0 e9 c2 fe ff ff 50 48 8d 3d 3a ca 0a 00 e8 f5 19 02 00 0f 1f 44 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 0f 05 <48> 3d 00 f0 ff ff 77 56 c3 0f 1f 44 00 00 48 83 ec 28 48 89 54 24 RSP: 002b:00007fff28eee5b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f0cdc819142 RDX: 0000000000020000 RSI: 00007f0cdc032000 RDI: 0000000000000003 RBP: 00007f0cdc032000 R08: 00007f0cdc031010 R09: 0000000000000000 R10: 0000000000000022 R11: 0000000000000246 R12: 00005607e9ee31f0 R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000Show less