Filtered by vendor Linux Subscriptions
Filtered by product Linux Kernel Subscriptions
Total 16990 CVE
CVE Vendors Products Updated CVSS v3.1
CVE-2023-53988 1 Linux 1 Linux Kernel 2025-12-29 N/A
In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: Fix slab-out-of-bounds read in hdr_delete_de() Here is a BUG report from syzbot: BUG: KASAN: slab-out-of-bounds in hdr_delete_de+0xe0/0x150 fs/ntfs3/index.c:806 Read of size 16842960 at addr ffff888079cc0600 by task syz-executor934/3631 Call Trace: memmove+0x25/0x60 mm/kasan/shadow.c:54 hdr_delete_de+0xe0/0x150 fs/ntfs3/index.c:806 indx_delete_entry+0x74f/0x3670 fs/ntfs3/index.c:2193 ni_remove_name+0x27a/0x980 fs/ntfs3/frecord.c:2910 ntfs_unlink_inode+0x3d4/0x720 fs/ntfs3/inode.c:1712 ntfs_rename+0x41a/0xcb0 fs/ntfs3/namei.c:276 Before using the meta-data in struct INDEX_HDR, we need to check index header valid or not. Otherwise, the corruptedi (or malicious) fs image can cause out-of-bounds access which could make kernel panic.
CVE-2023-54015 1 Linux 1 Linux Kernel 2025-12-29 7.0 High
In the Linux kernel, the following vulnerability has been resolved: net/mlx5: Devcom, fix error flow in mlx5_devcom_register_device In case devcom allocation is failed, mlx5 is always freeing the priv. However, this priv might have been allocated by a different thread, and freeing it might lead to use-after-free bugs. Fix it by freeing the priv only in case it was allocated by the running thread.
CVE-2023-53990 1 Linux 1 Linux Kernel 2025-12-29 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: SMB3: Add missing locks to protect deferred close file list cifs_del_deferred_close function has a critical section which modifies the deferred close file list. We must acquire deferred_lock before calling cifs_del_deferred_close function.
CVE-2023-53991 1 Linux 1 Linux Kernel 2025-12-29 N/A
In the Linux kernel, the following vulnerability has been resolved: drm/msm/dpu: Disallow unallocated resources to be returned In the event that the topology requests resources that have not been created by the system (because they are typically not represented in dpu_mdss_cfg ^1), the resource(s) in global_state (in this case DSC blocks, until their allocation/assignment is being sanity-checked in "drm/msm/dpu: Reject topologies for which no DSC blocks are available") remain NULL but will still be returned out of dpu_rm_get_assigned_resources, where the caller expects to get an array containing num_blks valid pointers (but instead gets these NULLs). To prevent this from happening, where null-pointer dereferences typically result in a hard-to-debug platform lockup, num_blks shouldn't increase past NULL blocks and will print an error and break instead. After all, max_blks represents the static size of the maximum number of blocks whereas the actual amount varies per platform. ^1: which can happen after a git rebase ended up moving additions to _dpu_cfg to a different struct which has the same patch context. Patchwork: https://patchwork.freedesktop.org/patch/517636/
CVE-2023-53993 1 Linux 1 Linux Kernel 2025-12-29 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: PCI/DOE: Fix memory leak with CONFIG_DEBUG_OBJECTS=y After a pci_doe_task completes, its work_struct needs to be destroyed to avoid a memory leak with CONFIG_DEBUG_OBJECTS=y.
CVE-2023-54012 1 Linux 1 Linux Kernel 2025-12-29 7.0 High
In the Linux kernel, the following vulnerability has been resolved: net: fix stack overflow when LRO is disabled for virtual interfaces When the virtual interface's feature is updated, it synchronizes the updated feature for its own lower interface. This propagation logic should be worked as the iteration, not recursively. But it works recursively due to the netdev notification unexpectedly. This problem occurs when it disables LRO only for the team and bonding interface type. team0 | +------+------+-----+-----+ | | | | | team1 team2 team3 ... team200 If team0's LRO feature is updated, it generates the NETDEV_FEAT_CHANGE event to its own lower interfaces(team1 ~ team200). It is worked by netdev_sync_lower_features(). So, the NETDEV_FEAT_CHANGE notification logic of each lower interface work iteratively. But generated NETDEV_FEAT_CHANGE event is also sent to the upper interface too. upper interface(team0) generates the NETDEV_FEAT_CHANGE event for its own lower interfaces again. lower and upper interfaces receive this event and generate this event again and again. So, the stack overflow occurs. But it is not the infinite loop issue. Because the netdev_sync_lower_features() updates features before generating the NETDEV_FEAT_CHANGE event. Already synchronized lower interfaces skip notification logic. So, it is just the problem that iteration logic is changed to the recursive unexpectedly due to the notification mechanism. Reproducer: ip link add team0 type team ethtool -K team0 lro on for i in {1..200} do ip link add team$i master team0 type team ethtool -K team$i lro on done ethtool -K team0 lro off In order to fix it, the notifier_ctx member of bonding/team is introduced.
CVE-2023-53994 1 Linux 1 Linux Kernel 2025-12-29 7.0 High
In the Linux kernel, the following vulnerability has been resolved: ionic: remove WARN_ON to prevent panic_on_warn Remove unnecessary early code development check and the WARN_ON that it uses. The irq alloc and free paths have long been cleaned up and this check shouldn't have stuck around so long.
CVE-2023-53995 1 Linux 1 Linux Kernel 2025-12-29 7.0 High
In the Linux kernel, the following vulnerability has been resolved: net: ipv4: fix one memleak in __inet_del_ifa() I got the below warning when do fuzzing test: unregister_netdevice: waiting for bond0 to become free. Usage count = 2 It can be repoduced via: ip link add bond0 type bond sysctl -w net.ipv4.conf.bond0.promote_secondaries=1 ip addr add 4.117.174.103/0 scope 0x40 dev bond0 ip addr add 192.168.100.111/255.255.255.254 scope 0 dev bond0 ip addr add 0.0.0.4/0 scope 0x40 secondary dev bond0 ip addr del 4.117.174.103/0 scope 0x40 dev bond0 ip link delete bond0 type bond In this reproduction test case, an incorrect 'last_prim' is found in __inet_del_ifa(), as a result, the secondary address(0.0.0.4/0 scope 0x40) is lost. The memory of the secondary address is leaked and the reference of in_device and net_device is leaked. Fix this problem: Look for 'last_prim' starting at location of the deleted IP and inserting the promoted IP into the location of 'last_prim'.
CVE-2023-53996 1 Linux 1 Linux Kernel 2025-12-29 7.0 High
In the Linux kernel, the following vulnerability has been resolved: x86/sev: Make enc_dec_hypercall() accept a size instead of npages enc_dec_hypercall() accepted a page count instead of a size, which forced its callers to round up. As a result, non-page aligned vaddrs caused pages to be spuriously marked as decrypted via the encryption status hypercall, which in turn caused consistent corruption of pages during live migration. Live migration requires accurate encryption status information to avoid migrating pages from the wrong perspective.
CVE-2023-54008 1 Linux 1 Linux Kernel 2025-12-29 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: virtio_vdpa: build affinity masks conditionally We try to build affinity mask via create_affinity_masks() unconditionally which may lead several issues: - the affinity mask is not used for parent without affinity support (only VDUSE support the affinity now) - the logic of create_affinity_masks() might not work for devices other than block. For example it's not rare in the networking device where the number of queues could exceed the number of CPUs. Such case breaks the current affinity logic which is based on group_cpus_evenly() who assumes the number of CPUs are not less than the number of groups. This can trigger a warning[1]: if (ret >= 0) WARN_ON(nr_present + nr_others < numgrps); Fixing this by only build the affinity masks only when - Driver passes affinity descriptor, driver like virtio-blk can make sure to limit the number of queues when it exceeds the number of CPUs - Parent support affinity setting config ops This help to avoid the warning. More optimizations could be done on top. [1] [ 682.146655] WARNING: CPU: 6 PID: 1550 at lib/group_cpus.c:400 group_cpus_evenly+0x1aa/0x1c0 [ 682.146668] CPU: 6 PID: 1550 Comm: vdpa Not tainted 6.5.0-rc5jason+ #79 [ 682.146671] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014 [ 682.146673] RIP: 0010:group_cpus_evenly+0x1aa/0x1c0 [ 682.146676] Code: 4c 89 e0 5b 5d 41 5c 41 5d 41 5e c3 cc cc cc cc e8 1b c4 74 ff 48 89 ef e8 13 ac 98 ff 4c 89 e7 45 31 e4 e8 08 ac 98 ff eb c2 <0f> 0b eb b6 e8 fd 05 c3 00 45 31 e4 eb e5 cc cc cc cc cc cc cc cc [ 682.146679] RSP: 0018:ffffc9000215f498 EFLAGS: 00010293 [ 682.146682] RAX: 000000000001f1e0 RBX: 0000000000000041 RCX: 0000000000000000 [ 682.146684] RDX: ffff888109922058 RSI: 0000000000000041 RDI: 0000000000000030 [ 682.146686] RBP: ffff888109922058 R08: ffffc9000215f498 R09: ffffc9000215f4a0 [ 682.146687] R10: 00000000000198d0 R11: 0000000000000030 R12: ffff888107e02800 [ 682.146689] R13: 0000000000000030 R14: 0000000000000030 R15: 0000000000000041 [ 682.146692] FS: 00007fef52315740(0000) GS:ffff888237380000(0000) knlGS:0000000000000000 [ 682.146695] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 682.146696] CR2: 00007fef52509000 CR3: 0000000110dbc004 CR4: 0000000000370ee0 [ 682.146698] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 682.146700] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 682.146701] Call Trace: [ 682.146703] <TASK> [ 682.146705] ? __warn+0x7b/0x130 [ 682.146709] ? group_cpus_evenly+0x1aa/0x1c0 [ 682.146712] ? report_bug+0x1c8/0x1e0 [ 682.146717] ? handle_bug+0x3c/0x70 [ 682.146721] ? exc_invalid_op+0x14/0x70 [ 682.146723] ? asm_exc_invalid_op+0x16/0x20 [ 682.146727] ? group_cpus_evenly+0x1aa/0x1c0 [ 682.146729] ? group_cpus_evenly+0x15c/0x1c0 [ 682.146731] create_affinity_masks+0xaf/0x1a0 [ 682.146735] virtio_vdpa_find_vqs+0x83/0x1d0 [ 682.146738] ? __pfx_default_calc_sets+0x10/0x10 [ 682.146742] virtnet_find_vqs+0x1f0/0x370 [ 682.146747] virtnet_probe+0x501/0xcd0 [ 682.146749] ? vp_modern_get_status+0x12/0x20 [ 682.146751] ? get_cap_addr.isra.0+0x10/0xc0 [ 682.146754] virtio_dev_probe+0x1af/0x260 [ 682.146759] really_probe+0x1a5/0x410
CVE-2023-53997 1 Linux 1 Linux Kernel 2025-12-29 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: thermal: of: fix double-free on unregistration Since commit 3d439b1a2ad3 ("thermal/core: Alloc-copy-free the thermal zone parameters structure"), thermal_zone_device_register() allocates a copy of the tzp argument and frees it when unregistering, so thermal_of_zone_register() now ends up leaking its original tzp and double-freeing the tzp copy. Fix this by locating tzp on stack instead.
CVE-2023-53998 1 Linux 1 Linux Kernel 2025-12-29 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: hwrng: virtio - Fix race on data_avail and actual data The virtio rng device kicks off a new entropy request whenever the data available reaches zero. When a new request occurs at the end of a read operation, that is, when the result of that request is only needed by the next reader, then there is a race between the writing of the new data and the next reader. This is because there is no synchronisation whatsoever between the writer and the reader. Fix this by writing data_avail with smp_store_release and reading it with smp_load_acquire when we first enter read. The subsequent reads are safe because they're either protected by the first load acquire, or by the completion mechanism. Also remove the redundant zeroing of data_idx in random_recv_done (data_idx must already be zero at this point) and data_avail in request_entropy (ditto).
CVE-2023-53999 1 Linux 1 Linux Kernel 2025-12-29 7.0 High
In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: TC, Fix internal port memory leak The flow rule can be splited, and the extra post_act rules are added to post_act table. It's possible to trigger memleak when the rule forwards packets from internal port and over tunnel, in the case that, for example, CT 'new' state offload is allowed. As int_port object is assigned to the flow attribute of post_act rule, and its refcnt is incremented by mlx5e_tc_int_port_get(), but mlx5e_tc_int_port_put() is not called, the refcnt is never decremented, then int_port is never freed. The kmemleak reports the following error: unreferenced object 0xffff888128204b80 (size 64): comm "handler20", pid 50121, jiffies 4296973009 (age 642.932s) hex dump (first 32 bytes): 01 00 00 00 19 00 00 00 03 f0 00 00 04 00 00 00 ................ 98 77 67 41 81 88 ff ff 98 77 67 41 81 88 ff ff .wgA.....wgA.... backtrace: [<00000000e992680d>] kmalloc_trace+0x27/0x120 [<000000009e945a98>] mlx5e_tc_int_port_get+0x3f3/0xe20 [mlx5_core] [<0000000035a537f0>] mlx5e_tc_add_fdb_flow+0x473/0xcf0 [mlx5_core] [<0000000070c2cec6>] __mlx5e_add_fdb_flow+0x7cf/0xe90 [mlx5_core] [<000000005cc84048>] mlx5e_configure_flower+0xd40/0x4c40 [mlx5_core] [<000000004f8a2031>] mlx5e_rep_indr_offload.isra.0+0x10e/0x1c0 [mlx5_core] [<000000007df797dc>] mlx5e_rep_indr_setup_tc_cb+0x90/0x130 [mlx5_core] [<0000000016c15cc3>] tc_setup_cb_add+0x1cf/0x410 [<00000000a63305b4>] fl_hw_replace_filter+0x38f/0x670 [cls_flower] [<000000008bc9e77c>] fl_change+0x1fd5/0x4430 [cls_flower] [<00000000e7f766e4>] tc_new_tfilter+0x867/0x2010 [<00000000e101c0ef>] rtnetlink_rcv_msg+0x6fc/0x9f0 [<00000000e1111d44>] netlink_rcv_skb+0x12c/0x360 [<0000000082dd6c8b>] netlink_unicast+0x438/0x710 [<00000000fc568f70>] netlink_sendmsg+0x794/0xc50 [<0000000016e92590>] sock_sendmsg+0xc5/0x190 So fix this by moving int_port cleanup code to the flow attribute free helper, which is used by all the attribute free cases.
CVE-2023-54000 1 Linux 1 Linux Kernel 2025-12-29 N/A
In the Linux kernel, the following vulnerability has been resolved: net: hns3: fix deadlock issue when externel_lb and reset are executed together When externel_lb and reset are executed together, a deadlock may occur: [ 3147.217009] INFO: task kworker/u321:0:7 blocked for more than 120 seconds. [ 3147.230483] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 3147.238999] task:kworker/u321:0 state:D stack: 0 pid: 7 ppid: 2 flags:0x00000008 [ 3147.248045] Workqueue: hclge hclge_service_task [hclge] [ 3147.253957] Call trace: [ 3147.257093] __switch_to+0x7c/0xbc [ 3147.261183] __schedule+0x338/0x6f0 [ 3147.265357] schedule+0x50/0xe0 [ 3147.269185] schedule_preempt_disabled+0x18/0x24 [ 3147.274488] __mutex_lock.constprop.0+0x1d4/0x5dc [ 3147.279880] __mutex_lock_slowpath+0x1c/0x30 [ 3147.284839] mutex_lock+0x50/0x60 [ 3147.288841] rtnl_lock+0x20/0x2c [ 3147.292759] hclge_reset_prepare+0x68/0x90 [hclge] [ 3147.298239] hclge_reset_subtask+0x88/0xe0 [hclge] [ 3147.303718] hclge_reset_service_task+0x84/0x120 [hclge] [ 3147.309718] hclge_service_task+0x2c/0x70 [hclge] [ 3147.315109] process_one_work+0x1d0/0x490 [ 3147.319805] worker_thread+0x158/0x3d0 [ 3147.324240] kthread+0x108/0x13c [ 3147.328154] ret_from_fork+0x10/0x18 In externel_lb process, the hns3 driver call napi_disable() first, then the reset happen, then the restore process of the externel_lb will fail, and will not call napi_enable(). When doing externel_lb again, napi_disable() will be double call, cause a deadlock of rtnl_lock(). This patch use the HNS3_NIC_STATE_DOWN state to protect the calling of napi_disable() and napi_enable() in externel_lb process, just as the usage in ndo_stop() and ndo_start().
CVE-2022-50702 1 Linux 1 Linux Kernel 2025-12-29 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: vdpa_sim: fix possible memory leak in vdpasim_net_init() and vdpasim_blk_init() Inject fault while probing module, if device_register() fails in vdpasim_net_init() or vdpasim_blk_init(), but the refcount of kobject is not decreased to 0, the name allocated in dev_set_name() is leaked. Fix this by calling put_device(), so that name can be freed in callback function kobject_cleanup(). (vdpa_sim_net) unreferenced object 0xffff88807eebc370 (size 16): comm "modprobe", pid 3848, jiffies 4362982860 (age 18.153s) hex dump (first 16 bytes): 76 64 70 61 73 69 6d 5f 6e 65 74 00 6b 6b 6b a5 vdpasim_net.kkk. backtrace: [<ffffffff8174f19e>] __kmalloc_node_track_caller+0x4e/0x150 [<ffffffff81731d53>] kstrdup+0x33/0x60 [<ffffffff83a5d421>] kobject_set_name_vargs+0x41/0x110 [<ffffffff82d87aab>] dev_set_name+0xab/0xe0 [<ffffffff82d91a23>] device_add+0xe3/0x1a80 [<ffffffffa0270013>] 0xffffffffa0270013 [<ffffffff81001c27>] do_one_initcall+0x87/0x2e0 [<ffffffff813739cb>] do_init_module+0x1ab/0x640 [<ffffffff81379d20>] load_module+0x5d00/0x77f0 [<ffffffff8137bc40>] __do_sys_finit_module+0x110/0x1b0 [<ffffffff83c4d505>] do_syscall_64+0x35/0x80 [<ffffffff83e0006a>] entry_SYSCALL_64_after_hwframe+0x46/0xb0 (vdpa_sim_blk) unreferenced object 0xffff8881070c1250 (size 16): comm "modprobe", pid 6844, jiffies 4364069319 (age 17.572s) hex dump (first 16 bytes): 76 64 70 61 73 69 6d 5f 62 6c 6b 00 6b 6b 6b a5 vdpasim_blk.kkk. backtrace: [<ffffffff8174f19e>] __kmalloc_node_track_caller+0x4e/0x150 [<ffffffff81731d53>] kstrdup+0x33/0x60 [<ffffffff83a5d421>] kobject_set_name_vargs+0x41/0x110 [<ffffffff82d87aab>] dev_set_name+0xab/0xe0 [<ffffffff82d91a23>] device_add+0xe3/0x1a80 [<ffffffffa0220013>] 0xffffffffa0220013 [<ffffffff81001c27>] do_one_initcall+0x87/0x2e0 [<ffffffff813739cb>] do_init_module+0x1ab/0x640 [<ffffffff81379d20>] load_module+0x5d00/0x77f0 [<ffffffff8137bc40>] __do_sys_finit_module+0x110/0x1b0 [<ffffffff83c4d505>] do_syscall_64+0x35/0x80 [<ffffffff83e0006a>] entry_SYSCALL_64_after_hwframe+0x46/0xb0
CVE-2023-54005 1 Linux 1 Linux Kernel 2025-12-29 N/A
In the Linux kernel, the following vulnerability has been resolved: binder: fix memory leak in binder_init() In binder_init(), the destruction of binder_alloc_shrinker_init() is not performed in the wrong path, which will cause memory leaks. So this commit introduces binder_alloc_shrinker_exit() and calls it in the wrong path to fix that.
CVE-2022-50704 1 Linux 1 Linux Kernel 2025-12-29 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: USB: gadget: Fix use-after-free during usb config switch In the process of switching USB config from rndis to other config, if the hardware does not support the ->pullup callback, or the hardware encounters a low probability fault, both of them may cause the ->pullup callback to fail, which will then cause a system panic (use after free). The gadget drivers sometimes need to be unloaded regardless of the hardware's behavior. Analysis as follows: ======================================================================= (1) write /config/usb_gadget/g1/UDC "none" gether_disconnect+0x2c/0x1f8 rndis_disable+0x4c/0x74 composite_disconnect+0x74/0xb0 configfs_composite_disconnect+0x60/0x7c usb_gadget_disconnect+0x70/0x124 usb_gadget_unregister_driver+0xc8/0x1d8 gadget_dev_desc_UDC_store+0xec/0x1e4 (2) rm /config/usb_gadget/g1/configs/b.1/f1 rndis_deregister+0x28/0x54 rndis_free+0x44/0x7c usb_put_function+0x14/0x1c config_usb_cfg_unlink+0xc4/0xe0 configfs_unlink+0x124/0x1c8 vfs_unlink+0x114/0x1dc (3) rmdir /config/usb_gadget/g1/functions/rndis.gs4 panic+0x1fc/0x3d0 do_page_fault+0xa8/0x46c do_mem_abort+0x3c/0xac el1_sync_handler+0x40/0x78 0xffffff801138f880 rndis_close+0x28/0x34 eth_stop+0x74/0x110 dev_close_many+0x48/0x194 rollback_registered_many+0x118/0x814 unregister_netdev+0x20/0x30 gether_cleanup+0x1c/0x38 rndis_attr_release+0xc/0x14 kref_put+0x74/0xb8 configfs_rmdir+0x314/0x374 If gadget->ops->pullup() return an error, function rndis_close() will be called, then it will causes a use-after-free problem. =======================================================================
CVE-2023-54018 1 Linux 1 Linux Kernel 2025-12-29 N/A
In the Linux kernel, the following vulnerability has been resolved: drm/msm/hdmi: Add missing check for alloc_ordered_workqueue Add check for the return value of alloc_ordered_workqueue as it may return NULL pointer and cause NULL pointer dereference in `hdmi_hdcp.c` and `hdmi_hpd.c`. Patchwork: https://patchwork.freedesktop.org/patch/517211/
CVE-2022-50706 1 Linux 1 Linux Kernel 2025-12-29 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: net/ieee802154: don't warn zero-sized raw_sendmsg() syzbot is hitting skb_assert_len() warning at __dev_queue_xmit() [1], for PF_IEEE802154 socket's zero-sized raw_sendmsg() request is hitting __dev_queue_xmit() with skb->len == 0. Since PF_IEEE802154 socket's zero-sized raw_sendmsg() request was able to return 0, don't call __dev_queue_xmit() if packet length is 0. ---------- #include <sys/socket.h> #include <netinet/in.h> int main(int argc, char *argv[]) { struct sockaddr_in addr = { .sin_family = AF_INET, .sin_addr.s_addr = htonl(INADDR_LOOPBACK) }; struct iovec iov = { }; struct msghdr hdr = { .msg_name = &addr, .msg_namelen = sizeof(addr), .msg_iov = &iov, .msg_iovlen = 1 }; sendmsg(socket(PF_IEEE802154, SOCK_RAW, 0), &hdr, 0); return 0; } ---------- Note that this might be a sign that commit fd1894224407c484 ("bpf: Don't redirect packets with invalid pkt_len") should be reverted, for skb->len == 0 was acceptable for at least PF_IEEE802154 socket.
CVE-2023-54041 1 Linux 1 Linux Kernel 2025-12-29 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: io_uring: fix memory leak when removing provided buffers When removing provided buffers, io_buffer structs are not being disposed of, leading to a memory leak. They can't be freed individually, because they are allocated in page-sized groups. They need to be added to some free list instead, such as io_buffers_cache. All callers already hold the lock protecting it, apart from when destroying buffers, so had to extend the lock there.