high CVSS 7.1

CVE-2024-56555·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: binder: fix OOB in binder_add_freeze_work() In binder_add_freeze_work() we iterate over the proc->nodes with the proc->inner_lock held. However, this lock is temporarily dropped to acquire the node->lock first (lock nesting order). This can race with binder_deferred_release() which removes the nodes from the proc->nodes rbtree and adds them into binder_dead_nodes list. This leads to a broken iteration in binder_add_freeze_work() as rb_next() will use data from binder_dead_nodes, triggering an out-of-bounds access: ================================================================== BUG: KASAN: global-out-of-bounds in rb_next+0xfc/0x124 Read of size 8 at addr ffffcb84285f7170 by task freeze/660 CPU: 8 UID: 0 PID: 660 Comm: freeze Not tainted 6.11.0-07343-ga727812a8d45 #18 Hardware name: linux,dummy-virt (DT) Call trace: rb_next+0xfc/0x124 binder_add_freeze_work+0x344/0x534 binder_ioctl+0x1e70/0x25ac __arm64_sys_ioctl+0x124/0x190 The buggy address belongs to the variable: binder_dead_nodes+0x10/0x40 [...] ================================================================== This is possible because proc->nodes (rbtree) and binder_dead_nodes (list) share entries in binder_node through a union: struct binder_node { [...] union { struct rb_node rb_node; struct hlist_node dead_node; }; Fix the race by checking that the proc is still alive. If not, simply break out of the iteration.

Severity
high
Software
Kernel
Fixed in
6.12.4
Published
2024-12-27

Affected versions

From: 6.12

Until: 6.12.4

Fixed in: 6.12.4

How to fix this CVE

Update your Linux kernel to version 6.12.4 or later to resolve this race condition in the binder subsystem. The vulnerability allows out-of-bounds memory access when concurrent operations manipulate node lists, potentially leading to kernel crash or information disclosure. Apply the kernel update immediately using your distribution's package manager and reboot the system to complete remediation.

sudo dnf update kernel kernel-devel && sudo reboot

Defensia detects this vulnerability

How to check if you are affected

  1. Check current kernel version: uname -r | grep -E '^6\.12\.[0-3]($|-)' to identify if running vulnerable versions 6.12.0 through 6.12.3
  2. Verify binder subsystem is in use: grep -i binder /proc/filesystems && ls -la /dev/binder* 2>/dev/null to confirm binder IPC is active
  3. Search system logs for crash signatures: dmesg | grep -i 'KASAN.*rb_next\|out-of-bounds\|binder_add_freeze_work' to detect exploitation attempts or kernel panics
  4. Confirm kernel update applied: uname -r should show version 6.12.4 or later, then verify with grep CONFIG_ANDROID_BINDER_IPC /boot/config-$(uname -r)

FAQ

What is CVE-2024-56555?

This vulnerability is a race condition in the Linux kernel's binder IPC subsystem where concurrent operations can cause an out-of-bounds memory access. When the binder_deferred_release() function removes nodes from a tree while binder_add_freeze_work() is iterating over them, the iterator accesses freed memory structures, triggering a KASAN out-of-bounds error.

Is CVE-2024-56555 being actively exploited?

No, this vulnerability is not currently listed as actively exploited according to CISA's Known Exploited Vulnerabilities (KEV) catalog, and no public exploit code is available.

What versions of Kernel are affected by CVE-2024-56555?

Linux kernel versions 6.12.0 through 6.12.3 are vulnerable. The fix was included in kernel version 6.12.4 and later.

How do I check if my server is vulnerable to CVE-2024-56555?

Run 'uname -r' to check your kernel version. If it shows 6.12.0, 6.12.1, 6.12.2, or 6.12.3, your system is vulnerable. Additionally, verify binder is enabled with 'grep CONFIG_ANDROID_BINDER_IPC /boot/config-$(uname -r)'.

Does Defensia detect CVE-2024-56555?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server running versions 6.12.0-6.12.3, CVE-2024-56555 will appear in your dashboard with remediation steps.

Related Kernel CVEs

CVE-2026-100075CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: RDMA/srpt: Fix srpt_alloc_rw_ctxs() unwind counters When srpt_alloc_rw_ctxs() fails partway through a multi-buffer indirect descriptor, the unwind path destroys RDMA contexts but leaves stale n_rw_ctx and n_rdma values (and a dangling rw_ctxs pointer). Later sq_wr_avail accounting in srpt_queue_response() or srpt_write_pending() can then subtract the wrong number of send queue credits. Reset the counters and clear rw_ctxs after freeing the heap allocation before returning an error.
CVE-2026-64397CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: ksmbd: serialize QUERY_DIRECTORY requests per file smb2_query_dir() stores a pointer to its stack-allocated private data in the ksmbd_file readdir_data. Concurrent QUERY_DIRECTORY requests using the same file handle can overwrite this pointer while an iterate_dir() callback is still using it, resulting in a stack use-after-free. Add a per-file mutex and hold it while accessing the shared directory enumeration state. The lock covers scan restart, dot entry state, readdir_data setup and iteration, and response construction. This prevents another request from replacing readdir_data.private before the current request has finished using it and also serializes the shared file position.
CVE-2026-64399CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE The FSCTL_DUPLICATE_EXTENTS_TO_FILE arm of smb2_ioctl() overwrites the destination file's data via vfs_clone_file_range() with neither the share-level KSMBD_TREE_CONN_FLAG_WRITABLE check nor a per-handle fp->daccess check that the other write-bearing arms carry. A client can overwrite destination data on a read-only share, or from a handle opened with only FILE_WRITE_ATTRIBUTES (which still yields an FMODE_WRITE filp). FILE_WRITE_ATTRIBUTES-only destination handle overwrote the file's data via the clone. Add both checks, matching the FSCTL_SET_SPARSE permission fix; require FILE_WRITE_DATA since this writes data.
CVE-2026-64066CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: netfs: Fix netfs_read_to_pagecache() to pause on subreq failure Fix netfs_read_to_pagecache() so that it pauses the generation of new subrequests if an already-issued subrequest fails.
CVE-2026-52924CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: sctp: purge outqueue on stale COOKIE-ECHO handling sctp_stream_update() is only invoked when the association is moved into COOKIE_WAIT during association setup/reconfiguration. In this path, the outbound stream scheduler state (stream->out_curr) is expected to be clean, since no user data should have been transmitted yet unless the state machine has already partially progressed. However, a corner case exists in sctp_sf_do_5_2_6_stale(): when a Stale Cookie ERROR is received, the association is rolled back from COOKIE_ECHOED to COOKIE_WAIT. In this scenario, user data may already have been queued and even bundled with the COOKIE-ECHO chunk. During the rollback, sctp_stream_update() frees the old stream table and installs a new one, but it does not invalidate stream->out_curr. As a result, out_curr may still point to a freed sctp_stream_out entry from the previous stream state. Later, SCTP scheduler dequeue paths (FCFS, RR, PRIO, etc.) rely on stream->out_curr->ext, which can lead to use-after-free once the old stream state has been released via sctp_stream_free(). This results in crashes such as (reported by Yuqi): BUG: KASAN: slab-use-after-free in sctp_sched_fcfs_dequeue+0x13a/0x140 Read of size 8 at addr ff1100004d4d3208 by task mini_poc/9312 CPU: 1 UID: 1001 PID: 9312 Comm: mini_poc Not tainted 7.1.0-rc1-00305-gbd3a4795d574 #5 PREEMPT(full) sctp_sched_fcfs_dequeue+0x13a/0x140 sctp_outq_flush+0x1603/0x33e0 sctp_do_sm+0x31c9/0x5d30 sctp_assoc_bh_rcv+0x392/0x6f0 sctp_inq_push+0x1db/0x270 sctp_rcv+0x138d/0x3c10 Fix this by fully purging the association outqueue when handling the Stale Cookie case. This ensures all pending transmit and retransmit state is dropped, and any scheduler cached pointers are invalidated, making it safe to rebuild stream state during COOKIE_WAIT restart. Updating only stream->out_curr would be insufficient, since queued and retransmittable data would still reference the old stream state and trigger later use-after-free in dequeue paths.

References

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