critical CVSS 9.8

CVE-2021-47378·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: nvme-rdma: destroy cm id before destroy qp to avoid use after free We should always destroy cm_id before destroy qp to avoid to get cma event after qp was destroyed, which may lead to use after free. In RDMA connection establishment error flow, don't destroy qp in cm event handler.Just report cm_error to upper level, qp will be destroy in nvme_rdma_alloc_queue() after destroy cm id.

Severity
critical
Software
Kernel
Fixed in
5.14.9
Published
2024-05-21

Affected versions

From: 5.11

Until: 5.14.9

Fixed in: 5.14.9

How to fix this CVE

Update your Linux kernel to version 5.14.9 or later to patch the NVMe RDMA memory safety issue. This vulnerability affects systems running kernel versions 5.11 through 5.14.8 where improper resource cleanup in the NVMe RDMA driver can lead to kernel crashes or memory corruption. Apply the latest kernel updates immediately and reboot your system to activate the patched version.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Run 'uname -r' to display your currently running kernel version and verify it is 5.14.9 or later
  2. Step 2: Check if NVMe RDMA is in use by running 'lsmod | grep nvme' and 'lsmod | grep rdma' to confirm the vulnerable drivers are loaded
  3. Step 3: Search kernel logs for RDMA-related errors using 'sudo journalctl -b | grep -i rdma' or 'sudo dmesg | grep -i rdma' to identify potential exploitation attempts
  4. Step 4: After applying updates, reboot the system with 'sudo reboot' and confirm the new kernel version is active with 'uname -r'

FAQ

What is CVE-2021-47378?

CVE-2021-47378 is a critical use-after-free vulnerability in the Linux kernel's NVMe RDMA driver where improper ordering of resource cleanup operations can allow the driver to access freed memory, potentially causing kernel crashes or memory corruption on systems using NVMe RDMA storage.

Is CVE-2021-47378 being actively exploited?

No, this vulnerability is not listed in CISA's Known Exploited Vulnerabilities catalog and no public exploits are currently available. However, its critical severity rating warrants immediate patching.

What versions of Kernel are affected by CVE-2021-47378?

Linux kernel versions 5.11 through 5.14.8 are vulnerable. The fix is available in kernel 5.14.9 and all later versions.

How do I check if my server is vulnerable to CVE-2021-47378?

Run 'uname -r' to check your kernel version. If it shows a version between 5.11 and 5.14.8, your system is vulnerable. Systems running 5.14.9 or later, or 5.10 and earlier, are not affected.

Does Defensia detect CVE-2021-47378?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Kernel is installed on a monitored server, CVE-2021-47378 will appear in your dashboard with remediation steps.

Related Kernel CVEs

CVE-2021-47274CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: tracing: Correct the length check which causes memory corruption We've suffered from severe kernel crashes due to memory corruption on our production environment, like, Call Trace: [1640542.554277] general protection fault: 0000 [#1] SMP PTI [1640542.554856] CPU: 17 PID: 26996 Comm: python Kdump: loaded Tainted:G [1640542.556629] RIP: 0010:kmem_cache_alloc+0x90/0x190 [1640542.559074] RSP: 0018:ffffb16faa597df8 EFLAGS: 00010286 [1640542.559587] RAX: 0000000000000000 RBX: 0000000000400200 RCX: 0000000006e931bf [1640542.560323] RDX: 0000000006e931be RSI: 0000000000400200 RDI: ffff9a45ff004300 [1640542.560996] RBP: 0000000000400200 R08: 0000000000023420 R09: 0000000000000000 [1640542.561670] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff9a20608d [1640542.562366] R13: ffff9a45ff004300 R14: ffff9a45ff004300 R15: 696c662f65636976 [1640542.563128] FS: 00007f45d7c6f740(0000) GS:ffff9a45ff840000(0000) knlGS:0000000000000000 [1640542.563937] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [1640542.564557] CR2: 00007f45d71311a0 CR3: 000000189d63e004 CR4: 00000000003606e0 [1640542.565279] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [1640542.566069] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [1640542.566742] Call Trace: [1640542.567009] anon_vma_clone+0x5d/0x170 [1640542.567417] __split_vma+0x91/0x1a0 [1640542.567777] do_munmap+0x2c6/0x320 [1640542.568128] vm_munmap+0x54/0x70 [1640542.569990] __x64_sys_munmap+0x22/0x30 [1640542.572005] do_syscall_64+0x5b/0x1b0 [1640542.573724] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [1640542.575642] RIP: 0033:0x7f45d6e61e27 James Wang has reproduced it stably on the latest 4.19 LTS. After some debugging, we finally proved that it's due to ftrace buffer out-of-bound access using a debug tool as follows: [ 86.775200] BUG: Out-of-bounds write at addr 0xffff88aefe8b7000 [ 86.780806] no_context+0xdf/0x3c0 [ 86.784327] __do_page_fault+0x252/0x470 [ 86.788367] do_page_fault+0x32/0x140 [ 86.792145] page_fault+0x1e/0x30 [ 86.795576] strncpy_from_unsafe+0x66/0xb0 [ 86.799789] fetch_memory_string+0x25/0x40 [ 86.804002] fetch_deref_string+0x51/0x60 [ 86.808134] kprobe_trace_func+0x32d/0x3a0 [ 86.812347] kprobe_dispatcher+0x45/0x50 [ 86.816385] kprobe_ftrace_handler+0x90/0xf0 [ 86.820779] ftrace_ops_assist_func+0xa1/0x140 [ 86.825340] 0xffffffffc00750bf [ 86.828603] do_sys_open+0x5/0x1f0 [ 86.832124] do_syscall_64+0x5b/0x1b0 [ 86.835900] entry_SYSCALL_64_after_hwframe+0x44/0xa9 commit b220c049d519 ("tracing: Check length before giving out the filter buffer") adds length check to protect trace data overflow introduced in 0fc1b09ff1ff, seems that this fix can't prevent overflow entirely, the length check should also take the sizeof entry->array[0] into account, since this array[0] is filled the length of trace data and occupy addtional space and risk overflow.
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References

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