Filtered by CWE-99
Total 233 CVE
CVE Vendors Products Updated CVSS v3.1
CVE-2024-40921 2024-11-05 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: net: bridge: mst: pass vlan group directly to br_mst_vlan_set_state Pass the already obtained vlan group pointer to br_mst_vlan_set_state() instead of dereferencing it again. Each caller has already correctly dereferenced it for their context. This change is required for the following suspicious RCU dereference fix. No functional changes intended.
CVE-2024-40918 2024-11-05 4.4 Medium
In the Linux kernel, the following vulnerability has been resolved: parisc: Try to fix random segmentation faults in package builds PA-RISC systems with PA8800 and PA8900 processors have had problems with random segmentation faults for many years. Systems with earlier processors are much more stable. Systems with PA8800 and PA8900 processors have a large L2 cache which needs per page flushing for decent performance when a large range is flushed. The combined cache in these systems is also more sensitive to non-equivalent aliases than the caches in earlier systems. The majority of random segmentation faults that I have looked at appear to be memory corruption in memory allocated using mmap and malloc. My first attempt at fixing the random faults didn't work. On reviewing the cache code, I realized that there were two issues which the existing code didn't handle correctly. Both relate to cache move-in. Another issue is that the present bit in PTEs is racy. 1) PA-RISC caches have a mind of their own and they can speculatively load data and instructions for a page as long as there is a entry in the TLB for the page which allows move-in. TLBs are local to each CPU. Thus, the TLB entry for a page must be purged before flushing the page. This is particularly important on SMP systems. In some of the flush routines, the flush routine would be called and then the TLB entry would be purged. This was because the flush routine needed the TLB entry to do the flush. 2) My initial approach to trying the fix the random faults was to try and use flush_cache_page_if_present for all flush operations. This actually made things worse and led to a couple of hardware lockups. It finally dawned on me that some lines weren't being flushed because the pte check code was racy. This resulted in random inequivalent mappings to physical pages. The __flush_cache_page tmpalias flush sets up its own TLB entry and it doesn't need the existing TLB entry. As long as we can find the pte pointer for the vm page, we can get the pfn and physical address of the page. We can also purge the TLB entry for the page before doing the flush. Further, __flush_cache_page uses a special TLB entry that inhibits cache move-in. When switching page mappings, we need to ensure that lines are removed from the cache. It is not sufficient to just flush the lines to memory as they may come back. This made it clear that we needed to implement all the required flush operations using tmpalias routines. This includes flushes for user and kernel pages. After modifying the code to use tmpalias flushes, it became clear that the random segmentation faults were not fully resolved. The frequency of faults was worse on systems with a 64 MB L2 (PA8900) and systems with more CPUs (rp4440). The warning that I added to flush_cache_page_if_present to detect pages that couldn't be flushed triggered frequently on some systems. Helge and I looked at the pages that couldn't be flushed and found that the PTE was either cleared or for a swap page. Ignoring pages that were swapped out seemed okay but pages with cleared PTEs seemed problematic. I looked at routines related to pte_clear and noticed ptep_clear_flush. The default implementation just flushes the TLB entry. However, it was obvious that on parisc we need to flush the cache page as well. If we don't flush the cache page, stale lines will be left in the cache and cause random corruption. Once a PTE is cleared, there is no way to find the physical address associated with the PTE and flush the associated page at a later time. I implemented an updated change with a parisc specific version of ptep_clear_flush. It fixed the random data corruption on Helge's rp4440 and rp3440, as well as on my c8000. At this point, I realized that I could restore the code where we only flush in flush_cache_page_if_present if the page has been accessed. However, for this, we also need to flush the cache when the accessed bit is cleared in ---truncated---
CVE-2024-39483 2 Linux, Redhat 2 Linux Kernel, Enterprise Linux 2024-11-05 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: WARN on vNMI + NMI window iff NMIs are outright masked When requesting an NMI window, WARN on vNMI support being enabled if and only if NMIs are actually masked, i.e. if the vCPU is already handling an NMI. KVM's ABI for NMIs that arrive simultanesouly (from KVM's point of view) is to inject one NMI and pend the other. When using vNMI, KVM pends the second NMI simply by setting V_NMI_PENDING, and lets the CPU do the rest (hardware automatically sets V_NMI_BLOCKING when an NMI is injected). However, if KVM can't immediately inject an NMI, e.g. because the vCPU is in an STI shadow or is running with GIF=0, then KVM will request an NMI window and trigger the WARN (but still function correctly). Whether or not the GIF=0 case makes sense is debatable, as the intent of KVM's behavior is to provide functionality that is as close to real hardware as possible. E.g. if two NMIs are sent in quick succession, the probability of both NMIs arriving in an STI shadow is infinitesimally low on real hardware, but significantly larger in a virtual environment, e.g. if the vCPU is preempted in the STI shadow. For GIF=0, the argument isn't as clear cut, because the window where two NMIs can collide is much larger in bare metal (though still small). That said, KVM should not have divergent behavior for the GIF=0 case based on whether or not vNMI support is enabled. And KVM has allowed simultaneous NMIs with GIF=0 for over a decade, since commit 7460fb4a3400 ("KVM: Fix simultaneous NMIs"). I.e. KVM's GIF=0 handling shouldn't be modified without a *really* good reason to do so, and if KVM's behavior were to be modified, it should be done irrespective of vNMI support.
CVE-2024-39481 1 Linux 1 Linux Kernel 2024-11-05 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: media: mc: Fix graph walk in media_pipeline_start The graph walk tries to follow all links, even if they are not between pads. This causes a crash with, e.g. a MEDIA_LNK_FL_ANCILLARY_LINK link. Fix this by allowing the walk to proceed only for MEDIA_LNK_FL_DATA_LINK links.
CVE-2024-39477 1 Linux 1 Linux Kernel 2024-11-05 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: mm/hugetlb: do not call vma_add_reservation upon ENOMEM sysbot reported a splat [1] on __unmap_hugepage_range(). This is because vma_needs_reservation() can return -ENOMEM if allocate_file_region_entries() fails to allocate the file_region struct for the reservation. Check for that and do not call vma_add_reservation() if that is the case, otherwise region_abort() and region_del() will see that we do not have any file_regions. If we detect that vma_needs_reservation() returned -ENOMEM, we clear the hugetlb_restore_reserve flag as if this reservation was still consumed, so free_huge_folio() will not increment the resv count. [1] https://lore.kernel.org/linux-mm/0000000000004096100617c58d54@google.com/T/#ma5983bc1ab18a54910da83416b3f89f3c7ee43aa
CVE-2024-39293 2024-11-05 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: Revert "xsk: Support redirect to any socket bound to the same umem" This reverts commit 2863d665ea41282379f108e4da6c8a2366ba66db. This patch introduced a potential kernel crash when multiple napi instances redirect to the same AF_XDP socket. By removing the queue_index check, it is possible for multiple napi instances to access the Rx ring at the same time, which will result in a corrupted ring state which can lead to a crash when flushing the rings in __xsk_flush(). This can happen when the linked list of sockets to flush gets corrupted by concurrent accesses. A quick and small fix is not possible, so let us revert this for now.
CVE-2024-38637 2024-11-05 4.4 Medium
In the Linux kernel, the following vulnerability has been resolved: greybus: lights: check return of get_channel_from_mode If channel for the given node is not found we return null from get_channel_from_mode. Make sure we validate the return pointer before using it in two of the missing places. This was originally reported in [0]: Found by Linux Verification Center (linuxtesting.org) with SVACE. [0] https://lore.kernel.org/all/20240301190425.120605-1-m.lobanov@rosalinux.ru
CVE-2024-38616 1 Linux 1 Linux Kernel 2024-11-05 8.2 High
In the Linux kernel, the following vulnerability has been resolved: wifi: carl9170: re-fix fortified-memset warning The carl9170_tx_release() function sometimes triggers a fortified-memset warning in my randconfig builds: In file included from include/linux/string.h:254, from drivers/net/wireless/ath/carl9170/tx.c:40: In function 'fortify_memset_chk', inlined from 'carl9170_tx_release' at drivers/net/wireless/ath/carl9170/tx.c:283:2, inlined from 'kref_put' at include/linux/kref.h:65:3, inlined from 'carl9170_tx_put_skb' at drivers/net/wireless/ath/carl9170/tx.c:342:9: include/linux/fortify-string.h:493:25: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning] 493 | __write_overflow_field(p_size_field, size); Kees previously tried to avoid this by using memset_after(), but it seems this does not fully address the problem. I noticed that the memset_after() here is done on a different part of the union (status) than the original cast was from (rate_driver_data), which may confuse the compiler. Unfortunately, the memset_after() trick does not work on driver_rates[] because that is part of an anonymous struct, and I could not get struct_group() to do this either. Using two separate memset() calls on the two members does address the warning though.
CVE-2024-38614 2024-11-05 4.4 Medium
In the Linux kernel, the following vulnerability has been resolved: openrisc: traps: Don't send signals to kernel mode threads OpenRISC exception handling sends signals to user processes on floating point exceptions and trap instructions (for debugging) among others. There is a bug where the trap handling logic may send signals to kernel threads, we should not send these signals to kernel threads, if that happens we treat it as an error. This patch adds conditions to die if the kernel receives these exceptions in kernel mode code.
CVE-2024-38610 2024-11-05 4.4 Medium
In the Linux kernel, the following vulnerability has been resolved: drivers/virt/acrn: fix PFNMAP PTE checks in acrn_vm_ram_map() Patch series "mm: follow_pte() improvements and acrn follow_pte() fixes". Patch #1 fixes a bunch of issues I spotted in the acrn driver. It compiles, that's all I know. I'll appreciate some review and testing from acrn folks. Patch #2+#3 improve follow_pte(), passing a VMA instead of the MM, adding more sanity checks, and improving the documentation. Gave it a quick test on x86-64 using VM_PAT that ends up using follow_pte(). This patch (of 3): We currently miss handling various cases, resulting in a dangerous follow_pte() (previously follow_pfn()) usage. (1) We're not checking PTE write permissions. Maybe we should simply always require pte_write() like we do for pin_user_pages_fast(FOLL_WRITE)? Hard to tell, so let's check for ACRN_MEM_ACCESS_WRITE for now. (2) We're not rejecting refcounted pages. As we are not using MMU notifiers, messing with refcounted pages is dangerous and can result in use-after-free. Let's make sure to reject them. (3) We are only looking at the first PTE of a bigger range. We only lookup a single PTE, but memmap->len may span a larger area. Let's loop over all involved PTEs and make sure the PFN range is actually contiguous. Reject everything else: it couldn't have worked either way, and rather made use access PFNs we shouldn't be accessing.
CVE-2024-38607 2024-11-05 4.4 Medium
In the Linux kernel, the following vulnerability has been resolved: macintosh/via-macii: Fix "BUG: sleeping function called from invalid context" The via-macii ADB driver calls request_irq() after disabling hard interrupts. But disabling interrupts isn't necessary here because the VIA shift register interrupt was masked during VIA1 initialization.
CVE-2024-38595 2024-11-05 4.4 Medium
In the Linux kernel, the following vulnerability has been resolved: net/mlx5: Fix peer devlink set for SF representor devlink port The cited patch change register devlink flow, and neglect to reflect the changes for peer devlink set logic. Peer devlink set is triggering a call trace if done after devl_register.[1] Hence, align peer devlink set logic with register devlink flow. [1] WARNING: CPU: 4 PID: 3394 at net/devlink/core.c:155 devlink_rel_nested_in_add+0x177/0x180 CPU: 4 PID: 3394 Comm: kworker/u40:1 Not tainted 6.9.0-rc4_for_linust_min_debug_2024_04_16_14_08 #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 Workqueue: mlx5_vhca_event0 mlx5_vhca_state_work_handler [mlx5_core] RIP: 0010:devlink_rel_nested_in_add+0x177/0x180 Call Trace: <TASK> ? __warn+0x78/0x120 ? devlink_rel_nested_in_add+0x177/0x180 ? report_bug+0x16d/0x180 ? handle_bug+0x3c/0x60 ? exc_invalid_op+0x14/0x70 ? asm_exc_invalid_op+0x16/0x20 ? devlink_port_init+0x30/0x30 ? devlink_port_type_clear+0x50/0x50 ? devlink_rel_nested_in_add+0x177/0x180 ? devlink_rel_nested_in_add+0xdd/0x180 mlx5_sf_mdev_event+0x74/0xb0 [mlx5_core] notifier_call_chain+0x35/0xb0 blocking_notifier_call_chain+0x3d/0x60 mlx5_blocking_notifier_call_chain+0x22/0x30 [mlx5_core] mlx5_sf_dev_probe+0x185/0x3e0 [mlx5_core] auxiliary_bus_probe+0x38/0x80 ? driver_sysfs_add+0x51/0x80 really_probe+0xc5/0x3a0 ? driver_probe_device+0x90/0x90 __driver_probe_device+0x80/0x160 driver_probe_device+0x1e/0x90 __device_attach_driver+0x7d/0x100 bus_for_each_drv+0x80/0xd0 __device_attach+0xbc/0x1f0 bus_probe_device+0x86/0xa0 device_add+0x64f/0x860 __auxiliary_device_add+0x3b/0xa0 mlx5_sf_dev_add+0x139/0x330 [mlx5_core] mlx5_sf_dev_state_change_handler+0x1e4/0x250 [mlx5_core] notifier_call_chain+0x35/0xb0 blocking_notifier_call_chain+0x3d/0x60 mlx5_vhca_state_work_handler+0x151/0x200 [mlx5_core] process_one_work+0x13f/0x2e0 worker_thread+0x2bd/0x3c0 ? rescuer_thread+0x410/0x410 kthread+0xc4/0xf0 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x2d/0x50 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork_asm+0x11/0x20 </TASK>
CVE-2024-38579 1 Redhat 1 Enterprise Linux 2024-11-05 4.4 Medium
In the Linux kernel, the following vulnerability has been resolved: crypto: bcm - Fix pointer arithmetic In spu2_dump_omd() value of ptr is increased by ciph_key_len instead of hash_iv_len which could lead to going beyond the buffer boundaries. Fix this bug by changing ciph_key_len to hash_iv_len. Found by Linux Verification Center (linuxtesting.org) with SVACE.
CVE-2024-38565 2024-11-05 6.5 Medium
In the Linux kernel, the following vulnerability has been resolved: wifi: ar5523: enable proper endpoint verification Syzkaller reports [1] hitting a warning about an endpoint in use not having an expected type to it. Fix the issue by checking for the existence of all proper endpoints with their according types intact. Sadly, this patch has not been tested on real hardware. [1] Syzkaller report: ------------[ cut here ]------------ usb 1-1: BOGUS urb xfer, pipe 3 != type 1 WARNING: CPU: 0 PID: 3643 at drivers/usb/core/urb.c:504 usb_submit_urb+0xed6/0x1880 drivers/usb/core/urb.c:504 ... Call Trace: <TASK> ar5523_cmd+0x41b/0x780 drivers/net/wireless/ath/ar5523/ar5523.c:275 ar5523_cmd_read drivers/net/wireless/ath/ar5523/ar5523.c:302 [inline] ar5523_host_available drivers/net/wireless/ath/ar5523/ar5523.c:1376 [inline] ar5523_probe+0x14b0/0x1d10 drivers/net/wireless/ath/ar5523/ar5523.c:1655 usb_probe_interface+0x30f/0x7f0 drivers/usb/core/driver.c:396 call_driver_probe drivers/base/dd.c:560 [inline] really_probe+0x249/0xb90 drivers/base/dd.c:639 __driver_probe_device+0x1df/0x4d0 drivers/base/dd.c:778 driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:808 __device_attach_driver+0x1d4/0x2e0 drivers/base/dd.c:936 bus_for_each_drv+0x163/0x1e0 drivers/base/bus.c:427 __device_attach+0x1e4/0x530 drivers/base/dd.c:1008 bus_probe_device+0x1e8/0x2a0 drivers/base/bus.c:487 device_add+0xbd9/0x1e90 drivers/base/core.c:3517 usb_set_configuration+0x101d/0x1900 drivers/usb/core/message.c:2170 usb_generic_driver_probe+0xbe/0x100 drivers/usb/core/generic.c:238 usb_probe_device+0xd8/0x2c0 drivers/usb/core/driver.c:293 call_driver_probe drivers/base/dd.c:560 [inline] really_probe+0x249/0xb90 drivers/base/dd.c:639 __driver_probe_device+0x1df/0x4d0 drivers/base/dd.c:778 driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:808 __device_attach_driver+0x1d4/0x2e0 drivers/base/dd.c:936 bus_for_each_drv+0x163/0x1e0 drivers/base/bus.c:427 __device_attach+0x1e4/0x530 drivers/base/dd.c:1008 bus_probe_device+0x1e8/0x2a0 drivers/base/bus.c:487 device_add+0xbd9/0x1e90 drivers/base/core.c:3517 usb_new_device.cold+0x685/0x10ad drivers/usb/core/hub.c:2573 hub_port_connect drivers/usb/core/hub.c:5353 [inline] hub_port_connect_change drivers/usb/core/hub.c:5497 [inline] port_event drivers/usb/core/hub.c:5653 [inline] hub_event+0x26cb/0x45d0 drivers/usb/core/hub.c:5735 process_one_work+0x9bf/0x1710 kernel/workqueue.c:2289 worker_thread+0x669/0x1090 kernel/workqueue.c:2436 kthread+0x2e8/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 </TASK>
CVE-2024-38384 2 Linux, Redhat 2 Linux Kernel, Rhel Eus 2024-11-05 8.4 High
In the Linux kernel, the following vulnerability has been resolved: blk-cgroup: fix list corruption from reorder of WRITE ->lqueued __blkcg_rstat_flush() can be run anytime, especially when blk_cgroup_bio_start is being executed. If WRITE of `->lqueued` is re-ordered with READ of 'bisc->lnode.next' in the loop of __blkcg_rstat_flush(), `next_bisc` can be assigned with one stat instance being added in blk_cgroup_bio_start(), then the local list in __blkcg_rstat_flush() could be corrupted. Fix the issue by adding one barrier.
CVE-2024-38381 1 Linux 1 Linux Kernel 2024-11-05 7.1 High
In the Linux kernel, the following vulnerability has been resolved: nfc: nci: Fix uninit-value in nci_rx_work syzbot reported the following uninit-value access issue [1] nci_rx_work() parses received packet from ndev->rx_q. It should be validated header size, payload size and total packet size before processing the packet. If an invalid packet is detected, it should be silently discarded.
CVE-2024-37078 2024-11-05 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix potential kernel bug due to lack of writeback flag waiting Destructive writes to a block device on which nilfs2 is mounted can cause a kernel bug in the folio/page writeback start routine or writeback end routine (__folio_start_writeback in the log below): kernel BUG at mm/page-writeback.c:3070! Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI ... RIP: 0010:__folio_start_writeback+0xbaa/0x10e0 Code: 25 ff 0f 00 00 0f 84 18 01 00 00 e8 40 ca c6 ff e9 17 f6 ff ff e8 36 ca c6 ff 4c 89 f7 48 c7 c6 80 c0 12 84 e8 e7 b3 0f 00 90 <0f> 0b e8 1f ca c6 ff 4c 89 f7 48 c7 c6 a0 c6 12 84 e8 d0 b3 0f 00 ... Call Trace: <TASK> nilfs_segctor_do_construct+0x4654/0x69d0 [nilfs2] nilfs_segctor_construct+0x181/0x6b0 [nilfs2] nilfs_segctor_thread+0x548/0x11c0 [nilfs2] kthread+0x2f0/0x390 ret_from_fork+0x4b/0x80 ret_from_fork_asm+0x1a/0x30 </TASK> This is because when the log writer starts a writeback for segment summary blocks or a super root block that use the backing device's page cache, it does not wait for the ongoing folio/page writeback, resulting in an inconsistent writeback state. Fix this issue by waiting for ongoing writebacks when putting folios/pages on the backing device into writeback state.
CVE-2024-36977 1 Redhat 1 Enterprise Linux 2024-11-05 4.7 Medium
In the Linux kernel, the following vulnerability has been resolved: usb: dwc3: Wait unconditionally after issuing EndXfer command Currently all controller IP/revisions except DWC3_usb3 >= 310a wait 1ms unconditionally for ENDXFER completion when IOC is not set. This is because DWC_usb3 controller revisions >= 3.10a supports GUCTL2[14: Rst_actbitlater] bit which allows polling CMDACT bit to know whether ENDXFER command is completed. Consider a case where an IN request was queued, and parallelly soft_disconnect was called (due to ffs_epfile_release). This eventually calls stop_active_transfer with IOC cleared, hence send_gadget_ep_cmd() skips waiting for CMDACT cleared during EndXfer. For DWC3 controllers with revisions >= 310a, we don't forcefully wait for 1ms either, and we proceed by unmapping the requests. If ENDXFER didn't complete by this time, it leads to SMMU faults since the controller would still be accessing those requests. Fix this by ensuring ENDXFER completion by adding 1ms delay in __dwc3_stop_active_transfer() unconditionally.
CVE-2024-36975 2024-11-05 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: KEYS: trusted: Do not use WARN when encode fails When asn1_encode_sequence() fails, WARN is not the correct solution. 1. asn1_encode_sequence() is not an internal function (located in lib/asn1_encode.c). 2. Location is known, which makes the stack trace useless. 3. Results a crash if panic_on_warn is set. It is also noteworthy that the use of WARN is undocumented, and it should be avoided unless there is a carefully considered rationale to use it. Replace WARN with pr_err, and print the return value instead, which is only useful piece of information.
CVE-2024-36963 2024-11-05 4.4 Medium
In the Linux kernel, the following vulnerability has been resolved: tracefs: Reset permissions on remount if permissions are options There's an inconsistency with the way permissions are handled in tracefs. Because the permissions are generated when accessed, they default to the root inode's permission if they were never set by the user. If the user sets the permissions, then a flag is set and the permissions are saved via the inode (for tracefs files) or an internal attribute field (for eventfs). But if a remount happens that specify the permissions, all the files that were not changed by the user gets updated, but the ones that were are not. If the user were to remount the file system with a given permission, then all files and directories within that file system should be updated. This can cause security issues if a file's permission was updated but the admin forgot about it. They could incorrectly think that remounting with permissions set would update all files, but miss some. For example: # cd /sys/kernel/tracing # chgrp 1002 current_tracer # ls -l [..] -rw-r----- 1 root root 0 May 1 21:25 buffer_size_kb -rw-r----- 1 root root 0 May 1 21:25 buffer_subbuf_size_kb -r--r----- 1 root root 0 May 1 21:25 buffer_total_size_kb -rw-r----- 1 root lkp 0 May 1 21:25 current_tracer -rw-r----- 1 root root 0 May 1 21:25 dynamic_events -r--r----- 1 root root 0 May 1 21:25 dyn_ftrace_total_info -r--r----- 1 root root 0 May 1 21:25 enabled_functions Where current_tracer now has group "lkp". # mount -o remount,gid=1001 . # ls -l -rw-r----- 1 root tracing 0 May 1 21:25 buffer_size_kb -rw-r----- 1 root tracing 0 May 1 21:25 buffer_subbuf_size_kb -r--r----- 1 root tracing 0 May 1 21:25 buffer_total_size_kb -rw-r----- 1 root lkp 0 May 1 21:25 current_tracer -rw-r----- 1 root tracing 0 May 1 21:25 dynamic_events -r--r----- 1 root tracing 0 May 1 21:25 dyn_ftrace_total_info -r--r----- 1 root tracing 0 May 1 21:25 enabled_functions Everything changed but the "current_tracer". Add a new link list that keeps track of all the tracefs_inodes which has the permission flags that tell if the file/dir should use the root inode's permission or not. Then on remount, clear all the flags so that the default behavior of using the root inode's permission is done for all files and directories.