CVE-2024-36907 in Linux
Summary
by MITRE • 05/30/2024
In the Linux kernel, the following vulnerability has been resolved:
SUNRPC: add a missing rpc_stat for TCP TLS
Commit 1548036ef120 ("nfs: make the rpc_stat per net namespace") added functionality to specify rpc_stats function but missed adding it to the TCP TLS functionality. As the result, mounting with xprtsec=tls lead to the following kernel oops.
[ 128.984192] Unable to handle kernel NULL pointer dereference at
virtual address 000000000000001c [ 128.985058] Mem abort info:
[ 128.985372] ESR = 0x0000000096000004
[ 128.985709] EC = 0x25: DABT (current EL), IL = 32 bits
[ 128.986176] SET = 0, FnV = 0
[ 128.986521] EA = 0, S1PTW = 0
[ 128.986804] FSC = 0x04: level 0 translation fault
[ 128.987229] Data abort info:
[ 128.987597] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
[ 128.988169] CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[ 128.988811] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[ 128.989302] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000106c84000
[ 128.990048] [000000000000001c] pgd=0000000000000000, p4d=0000000000000000
[ 128.990736] Internal error: Oops: 0000000096000004 [#1] SMP
[ 128.991168] Modules linked in: nfs_layout_nfsv41_files
rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver nfs lockd grace netfs uinput dm_mod nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 rfkill ip_set nf_tables nfnetlink qrtr vsock_loopback vmw_vsock_virtio_transport_common vmw_vsock_vmci_transport vsock sunrpc vfat fat uvcvideo videobuf2_vmalloc videobuf2_memops uvc videobuf2_v4l2 videodev videobuf2_common mc vmw_vmci xfs libcrc32c e1000e crct10dif_ce ghash_ce sha2_ce vmwgfx nvme sha256_arm64 nvme_core sr_mod cdrom sha1_ce drm_ttm_helper ttm drm_kms_helper drm sg fuse [ 128.996466] CPU: 0 PID: 179 Comm: kworker/u4:26 Kdump: loaded Not
tainted 6.8.0-rc6+ #12 [ 128.997226] Hardware name: VMware, Inc. VMware20,1/VBSA, BIOS
VMW201.00V.21805430.BA64.2305221830 05/22/2023 [ 128.998084] Workqueue: xprtiod xs_tcp_tls_setup_socket [sunrpc]
[ 128.998701] pstate: 81400005 (Nzcv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
[ 128.999384] pc : call_start+0x74/0x138 [sunrpc]
[ 128.999809] lr : __rpc_execute+0xb8/0x3e0 [sunrpc]
[ 129.000244] sp : ffff8000832b3a00
[ 129.000508] x29: ffff8000832b3a00 x28: ffff800081ac79c0 x27: ffff800081ac7000
[ 129.001111] x26: 0000000004248060 x25: 0000000000000000 x24: ffff800081596008
[ 129.001757] x23: ffff80007b087240 x22: ffff00009a509d30 x21: 0000000000000000
[ 129.002345] x20: ffff000090075600 x19: ffff00009a509d00 x18: ffffffffffffffff
[ 129.002912] x17: 733d4d4554535953 x16: 42555300312d746e x15: ffff8000832b3a88
[ 129.003464] x14: ffffffffffffffff x13: ffff8000832b3a7d x12: 0000000000000008
[ 129.004021] x11: 0101010101010101 x10: ffff8000150cb560 x9 : ffff80007b087c00
[ 129.004577] x8 : ffff00009a509de0 x7 : 0000000000000000 x6 : 00000000be8c4ee3
[ 129.005026] x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff000094d56680
[ 129.005425] x2 : ffff80007b0637f8 x1 : ffff000090075600 x0 : ffff00009a509d00
[ 129.005824] Call trace:
[ 129.005967] call_start+0x74/0x138 [sunrpc]
[ 129.006233] __rpc_execute+0xb8/0x3e0 [sunrpc]
[ 129.006506] rpc_execute+0x160/0x1d8 [sunrpc]
[ 129.006778] rpc_run_task+0x148/0x1f8 [sunrpc]
[ 129.007204] tls_probe+0x80/0xd0 [sunrpc]
[ 129.007460] rpc_ping+0x28/0x80 [sunrpc]
[ 129.007715] rpc_create_xprt+0x134/0x1a0 [sunrpc]
[ 129.007999] rpc_create+0x128/0x2a0 [sunrpc]
[ 129.008264] xs_tcp_tls_setup_socket+0xdc/0x508 [sunrpc]
[ 129.008583] process_one_work+0x174/0x3c8
[ 129.008813] worker_thread+0x2c8/0x3e0
[ 129.009033] kthread+0x100/0x110
[ 129.009225] ret_from_fork+0x10/0x20
[ 129.009432] Code: f0ffffc2 911fe042 aa1403e1 aa1303e0 (b9401c83)
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Analysis
by VulDB Data Team • 06/26/2026
This vulnerability resides within the Linux kernel's sunrpc subsystem and specifically affects the rpc_stat functionality for TCP TLS transport mechanisms. The issue stems from a missing rpc_stat function registration that was introduced in commit 1548036ef120 which implemented per network namespace rpc_stats functionality. During the implementation, developers inadvertently omitted the necessary registration of the rpc_stat function for TCP TLS connections, creating a critical gap in the kernel's transport layer management.
The technical flaw manifests as a null pointer dereference when attempting to mount NFS shares using xprtsec=tls parameter. The kernel oops traceback shows the failure occurs during socket setup operations within the xs_tcp_tls_setup_socket function where the system attempts to access an uninitialized rpc_stat structure at virtual address 0x1c. This memory location represents a critical data structure pointer that should contain valid function pointers for statistics collection but instead contains a null value, leading to immediate kernel panic and system crash.
The operational impact of this vulnerability is severe as it completely prevents NFS mounts using TLS security mechanisms, effectively breaking secure network file sharing capabilities on affected systems. The vulnerability affects systems running kernel versions where the problematic commit was introduced, particularly impacting enterprise environments that rely on encrypted NFS communications for data protection. The crash occurs during normal mount operations, making it a critical issue for system administrators managing network storage infrastructure.
The root cause aligns with CWE-476 which describes NULL pointer dereference vulnerabilities in software systems. This flaw also relates to ATT&CK technique T1566 which involves the exploitation of software vulnerabilities to gain unauthorized access or disrupt services. The vulnerability demonstrates a classic oversight in kernel development where new features are added without proper integration testing across all existing subsystems, particularly when dealing with complex transport layer protocols that require comprehensive state management.
Mitigation strategies include applying the appropriate kernel patch that properly registers the rpc_stat function for TCP TLS connections, ensuring that all transport mechanisms maintain consistent interface implementations. System administrators should prioritize updating to patched kernel versions and validate that NFS mounts using xprtsec=tls parameter function correctly after patch application. Additionally, monitoring systems should be configured to detect potential kernel oops conditions related to sunrpc subsystem operations, as this vulnerability could serve as an indicator of more sophisticated attacks targeting kernel-level components.