medium CVSS 5.5 EPSS <0.1%

CVE-2023-52817·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu: Fix a null pointer access when the smc_rreg pointer is NULL In certain types of chips, such as VEGA20, reading the amdgpu_regs_smc file could result in an abnormal null pointer access when the smc_rreg pointer is NULL. Below are the steps to reproduce this issue and the corresponding exception log: 1. Navigate to the directory: /sys/kernel/debug/dri/0 2. Execute command: cat amdgpu_regs_smc 3. Exception Log:: [4005007.702554] BUG: kernel NULL pointer dereference, address: 0000000000000000 [4005007.702562] #PF: supervisor instruction fetch in kernel mode [4005007.702567] #PF: error_code(0x0010) - not-present page [4005007.702570] PGD 0 P4D 0 [4005007.702576] Oops: 0010 [#1] SMP NOPTI [4005007.702581] CPU: 4 PID: 62563 Comm: cat Tainted: G OE 5.15.0-43-generic #46-Ubunt u [4005007.702590] RIP: 0010:0x0 [4005007.702598] Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6. [4005007.702600] RSP: 0018:ffffa82b46d27da0 EFLAGS: 00010206 [4005007.702605] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffa82b46d27e68 [4005007.702609] RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff9940656e0000 [4005007.702612] RBP: ffffa82b46d27dd8 R08: 0000000000000000 R09: ffff994060c07980 [4005007.702615] R10: 0000000000020000 R11: 0000000000000000 R12: 00007f5e06753000 [4005007.702618] R13: ffff9940656e0000 R14: ffffa82b46d27e68 R15: 00007f5e06753000 [4005007.702622] FS: 00007f5e0755b740(0000) GS:ffff99479d300000(0000) knlGS:0000000000000000 [4005007.702626] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [4005007.702629] CR2: ffffffffffffffd6 CR3: 00000003253fc000 CR4: 00000000003506e0 [4005007.702633] Call Trace: [4005007.702636] <TASK> [4005007.702640] amdgpu_debugfs_regs_smc_read+0xb0/0x120 [amdgpu] [4005007.703002] full_proxy_read+0x5c/0x80 [4005007.703011] vfs_read+0x9f/0x1a0 [4005007.703019] ksys_read+0x67/0xe0 [4005007.703023] __x64_sys_read+0x19/0x20 [4005007.703028] do_syscall_64+0x5c/0xc0 [4005007.703034] ? do_user_addr_fault+0x1e3/0x670 [4005007.703040] ? exit_to_user_mode_prepare+0x37/0xb0 [4005007.703047] ? irqentry_exit_to_user_mode+0x9/0x20 [4005007.703052] ? irqentry_exit+0x19/0x30 [4005007.703057] ? exc_page_fault+0x89/0x160 [4005007.703062] ? asm_exc_page_fault+0x8/0x30 [4005007.703068] entry_SYSCALL_64_after_hwframe+0x44/0xae [4005007.703075] RIP: 0033:0x7f5e07672992 [4005007.703079] Code: c0 e9 b2 fe ff ff 50 48 8d 3d fa b2 0c 00 e8 c5 1d 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 e c 28 48 89 54 24 [4005007.703083] RSP: 002b:00007ffe03097898 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [4005007.703088] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f5e07672992 [4005007.703091] RDX: 0000000000020000 RSI: 00007f5e06753000 RDI: 0000000000000003 [4005007.703094] RBP: 00007f5e06753000 R08: 00007f5e06752010 R09: 00007f5e06752010 [4005007.703096] R10: 0000000000000022 R11: 0000000000000246 R12: 0000000000022000 [4005007.703099] R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000 [4005007.703105] </TASK> [4005007.703107] Modules linked in: nf_tables libcrc32c nfnetlink algif_hash af_alg binfmt_misc nls_ iso8859_1 ipmi_ssif ast intel_rapl_msr intel_rapl_common drm_vram_helper drm_ttm_helper amd64_edac t tm edac_mce_amd kvm_amd ccp mac_hid k10temp kvm acpi_ipmi ipmi_si rapl sch_fq_codel ipmi_devintf ipm i_msghandler msr parport_pc ppdev lp parport mtd pstore_blk efi_pstore ramoops pstore_zone reed_solo mon ip_tables x_tables autofs4 ib_uverbs ib_core amdgpu(OE) amddrm_ttm_helper(OE) amdttm(OE) iommu_v 2 amd_sched(OE) amdkcl(OE) drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops cec rc_core drm igb ahci xhci_pci libahci i2c_piix4 i2c_algo_bit xhci_pci_renesas dca [4005007.703184] CR2: 0000000000000000 [4005007.703188] ---[ en ---truncated---

Severity
medium
Software
Kernel
Fixed in
6.6.3
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at <0.1% — higher than 1% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Affected versions

From: 6.6

Until: 6.6.3

Fixed in: 6.6.3

How to fix this CVE

Update your Linux kernel to version 6.6.3 or later to resolve this null pointer dereference vulnerability affecting AMD GPU driver debugging functionality. The issue occurs when reading SMC (System Management Controller) registers on certain VEGA20 chips, causing a kernel crash. Apply the patch by updating your kernel package through your distribution's package manager.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Run `uname -r` to check your current kernel version; vulnerable versions are 6.6.0 through 6.6.2
  2. Check if AMD GPU drivers are loaded with `lsmod | grep amdgpu`; if not present, this system is not affected
  3. Review kernel logs for null pointer dereference errors with `dmesg | grep -i 'amdgpu_debugfs_regs_smc_read'` or `dmesg | grep -i 'null pointer'`
  4. Verify the fix by confirming kernel version is 6.6.3+ with `uname -r`, then attempt to safely read the SMC register file with `cat /sys/kernel/debug/dri/0/amdgpu_regs_smc` without kernel crashes

FAQ

What is CVE-2023-52817?

This vulnerability is a null pointer dereference in the AMD GPU driver's debugfs interface that occurs when the SMC (System Management Controller) register read function pointer is uninitialized on certain VEGA20 GPU chips, allowing local users to crash the kernel by accessing a debug file.

Is CVE-2023-52817 being actively exploited?

No, this vulnerability is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog and no public exploits are currently available. However, any local user with access to debugfs can trigger a denial-of-service condition.

What versions of Kernel are affected by CVE-2023-52817?

Linux kernel versions 6.6.0 through 6.6.2 are affected. The vulnerability is fixed in kernel 6.6.3 and later.

How do I check if my server is vulnerable to CVE-2023-52817?

Run `uname -r` to check your kernel version. If it shows 6.6.0, 6.6.1, or 6.6.2 AND you have AMD GPU support enabled (check with `lsmod | grep amdgpu`), your system is vulnerable.

Does Defensia detect CVE-2023-52817?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server, CVE-2023-52817 will appear in your dashboard with remediation steps.

Related Kernel CVEs

CVE-2026-63795CVSS 10In the Linux kernel, the following vulnerability has been resolved: 9p: avoid putting oldfid in p9_client_walk() error path When p9_client_walk() is called with clone set to false, fid aliases oldfid. If the walk subsequently fails after the request has been sent, the error path jumps to clunk_fid, which currently calls p9_fid_put(fid) unconditionally. This drops a reference to oldfid even though ownership of oldfid remains with the caller. If this is the last reference, oldfid can be clunked and destroyed while the caller still expects it to be valid. A later use or put of oldfid can then trigger a use-after-free or refcount underflow. Fix this by only putting fid in the clunk_fid error path when it does not alias oldfid, matching the existing guard in the error path below. This can be triggered when a multi-component walk is split into multiple p9_client_walk() calls and a later non-cloning walk fails. A reproducer and refcount warning logs are available on request.
CVE-2026-46325CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: RDMA/rxe: Fix iova-to-va conversion for MR page sizes != PAGE_SIZE The current implementation incorrectly handles memory regions (MRs) with page sizes different from the system PAGE_SIZE. The core issue is that rxe_set_page() is called with mr->page_size step increments, but the page_list stores individual struct page pointers, each representing PAGE_SIZE of memory. ib_sg_to_page() has ensured that when i>=1 either a) SG[i-1].dma_end and SG[i].dma_addr are contiguous or b) SG[i-1].dma_end and SG[i].dma_addr are mr->page_size aligned. This leads to incorrect iova-to-va conversion in scenarios: 1) page_size < PAGE_SIZE (e.g., MR: 4K, system: 64K): ibmr->iova = 0x181800 sg[0]: dma_addr=0x181800, len=0x800 sg[1]: dma_addr=0x173000, len=0x1000 Access iova = 0x181800 + 0x810 = 0x182010 Expected VA: 0x173010 (second SG, offset 0x10) Before fix: - index = (0x182010 >> 12) - (0x181800 >> 12) = 1 - page_offset = 0x182010 & 0xFFF = 0x10 - xarray[1] stores system page base 0x170000 - Resulting VA: 0x170000 + 0x10 = 0x170010 (wrong) 2) page_size > PAGE_SIZE (e.g., MR: 64K, system: 4K): ibmr->iova = 0x18f800 sg[0]: dma_addr=0x18f800, len=0x800 sg[1]: dma_addr=0x170000, len=0x1000 Access iova = 0x18f800 + 0x810 = 0x190010 Expected VA: 0x170010 (second SG, offset 0x10) Before fix: - index = (0x190010 >> 16) - (0x18f800 >> 16) = 1 - page_offset = 0x190010 & 0xFFFF = 0x10 - xarray[1] stores system page for dma_addr 0x170000 - Resulting VA: system page of 0x170000 + 0x10 = 0x170010 (wrong) Yi Zhang reported a kernel panic[1] years ago related to this defect. Solution: 1. Replace xarray with pre-allocated rxe_mr_page array for sequential indexing (all MR page indices are contiguous) 2. Each rxe_mr_page stores both struct page* and offset within the system page 3. Handle MR page_size != PAGE_SIZE relationships: - page_size > PAGE_SIZE: Split MR pages into multiple system pages - page_size <= PAGE_SIZE: Store offset within system page 4. Add boundary checks and compatibility validation This ensures correct iova-to-va conversion regardless of MR page size and system PAGE_SIZE relationship, while improving performance through array-based sequential access. Tests on 4K and 64K PAGE_SIZE hosts: - rdma-core/pytests $ ./build/bin/run_tests.py --dev eth0_rxe - blktest: $ TIMEOUT=30 QUICK_RUN=1 USE_RXE=1 NVMET_TRTYPES=rdma ./check nvme srp rnbd [1] https://lore.kernel.org/all/CAHj4cs9XRqE25jyVw9rj9YugffLn5+f=1znaBEnu1usLOciD+g@mail.gmail.com/T/
CVE-2026-52914CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: batman-adv: fix fragment reassembly length accounting batman-adv keeps a running payload length for queued fragments and uses it to validate a fragment chain before reassembly. That accounting currently allows the accumulated fragment length to be truncated during updates. As a result, malformed fragment chains can bypass the intended validation and drive reassembly with inconsistent length state, leading to a local denial of service. Fix the accounting by storing the accumulated length in a length-typed field and rejecting update overflows before the existing validation logic runs. The fix was verified against the original reproducer and against valid fragment reassembly paths.
CVE-2026-53151CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: rxrpc: Fix the ACK parser to extract the SACK table for parsing Fix modification of the received skbuff in rxrpc_input_soft_acks() and a potential incorrect access of the buffer in a fragmented UDP packet (the packet would probably have to be deliberately pre-generated as fragmented) when AF_RXRPC tries to extract the contents of the SACK table by copying out the contents of the SACK table into a buffer before attempting to parse AF_RXRPC assumes that it can just call skb_condense() and then validly access the SACK table from skb->data and that it will be a flat buffer - but skb_condense() can silently fail to do anything under some circumstances. Note that whilst rxrpc_input_soft_acks() should be able to parse extended ACKs, the rest of AF_RXRPC doesn't currently support that. Further, there's then no need to call skb_condense() in rxrpc_input_ack(), so don't.
CVE-2026-63800CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: pNFS: Fix use-after-free in pnfs_update_layout() When hitting the NFS_LAYOUT_RETURN branch in pnfs_update_layout(), the code calls pnfs_prepare_to_retry_layoutget(lo). If it succeeds, pnfs_put_layout_hdr(lo) is called before trace_pnfs_update_layout(), which still references 'lo'. This results in a use-after-free when the tracepoint accesses lo's fields. Fix this by moving the tracepoint call before pnfs_put_layout_hdr(lo).

References

Track CVEs across your fleet automatically

Defensia scans your Linux servers and tells you exactly which ones are running vulnerable versions — including CVE-2023-52817. Free for 1 server.

Get started free