CVE-2026-63810

block: Avoid mounting the bdev pseudo-filesystem in userspace

published

In the Linux kernel, the following vulnerability has been resolved: block: Avoid mounting the bdev pseudo-filesystem in userspace The bdev pseudo-filesystem is an internal kernel filesystem with which userspace should not interfere. Unregister it so that userspace cannot even attempt to mount it. This fixes a bug [1] that occurs when attempting to access files, because the system call move_mount() uses pointers declared in the inode_operations structure, which for the bdev pseudo-filesystem are always equal to 0. `inode->i_op = &empty_iops;` [1] BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page PGD 23380067 P4D 23380067 PUD 23381067 PMD 0 Oops: 0010 [#1] PREEMPT SMP KASAN NOPTI CPU: 2 PID: 17125 Comm: syz-executor.0 Not tainted 6.1.155-syzkaller-00350-g84221fde2681 #0 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 RIP: 0010:0x0 Call Trace: <TASK> lookup_open.isra.0+0x700/0x1180 fs/namei.c:3460 open_last_lookups fs/namei.c:3550 [inline] path_openat+0x953/0x2700 fs/namei.c:3780 do_filp_open+0x1c5/0x410 fs/namei.c:3810 do_sys_openat2+0x171/0x4d0 fs/open.c:1318 do_sys_open fs/open.c:1334 [inline] __do_sys_openat fs/open.c:1350 [inline] __se_sys_openat fs/open.c:1345 [inline] __x64_sys_openat+0x13c/0x1f0 fs/open.c:1345 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x6e/0xd8 Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Technical severityUnscoredNo score in collected sources

Published2026-07-19Source updated 2026-11-10

Collected2026-11-103 attributed sources

Fixes and workarounds

No remediation reported in collected sources.

Missing remediation information is not evidence that no patch exists.

Affected products and versions

Affected products, source version ranges and reporting authorities
Product	Versions	Authority
Linux Linux	≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < 3d3fcf23993bb756de2f912ab631cfdcc4746554 (affected, git) ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < 99cde0a7b1e98fd3970aabef1300918e91698dd5 (affected, git) ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < 1a02a5028bd6dead1f8503854ef3168d651cd417 (affected, git) ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < 197971e6ffc0a6356b2ba2b22beb42bc0f7e412d (affected, git) ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < 3804e6de30ae7b053d53341d9d6944356cf23b40 (affected, git) ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < 717f721eb67d2dacd3ed5f7495aef2f442e84ce4 (affected, git) ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2; < f73aa66dffcb8e61e78f01b56163ec16a15d06d2 (affected, git) Other versions: unaffected	CNA: Linux
Linux Linux	2.6.12 (affected) ≥ 0; < 2.6.12 (unaffected, semver) ≥ 5.15.212; ≤ 5.15.* (unaffected, semver) ≥ 6.1.178; ≤ 6.1.* (unaffected, semver) ≥ 6.6.145; ≤ 6.6.* (unaffected, semver) ≥ 6.12.95; ≤ 6.12.* (unaffected, semver) ≥ 6.18.38; ≤ 6.18.* (unaffected, semver) ≥ 7.1.3; ≤ 7.1.* (unaffected, semver) ≥ 7.2; ≤ * (unaffected, original_commit_for_fix) Other versions: affected	CNA: Linux
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) Siemens	≥ V3.1.6; < * (affected, custom) Other versions: unknown	ADP: siemens-SADP
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) Siemens	≥ V3.1.7; < * (affected, custom) Other versions: unknown	ADP: siemens-SADP
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) Siemens	≥ V3.1.6; < * (affected, custom) Other versions: unknown	ADP: siemens-SADP
SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) Siemens	≥ V3.1.7; < * (affected, custom) Other versions: unknown	ADP: siemens-SADP
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) Siemens	≥ V3.1.6; < * (affected, custom) Other versions: unknown	ADP: siemens-SADP
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) Siemens	≥ V3.1.7; < * (affected, custom) Other versions: unknown	ADP: siemens-SADP
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) Siemens	≥ V3.1.6; < * (affected, custom) Other versions: unknown	ADP: siemens-SADP
SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) Siemens	≥ V3.1.7; < * (affected, custom) Other versions: unknown	ADP: siemens-SADP
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) Siemens	≥ V3.1.6; < * (affected, custom) Other versions: unknown	ADP: siemens-SADP
SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) Siemens	≥ V3.1.7; < * (affected, custom) Other versions: unknown	ADP: siemens-SADP

Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.

CVSS assessments

No CVSS assessment reported. An unscored record is not a low-severity determination.

Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

References

https://git.kernel.org/stable/c/3d3fcf23993bb756de2f912ab631cfdcc4746554CNA: Linux
https://git.kernel.org/stable/c/99cde0a7b1e98fd3970aabef1300918e91698dd5CNA: Linux
https://git.kernel.org/stable/c/1a02a5028bd6dead1f8503854ef3168d651cd417CNA: Linux
https://git.kernel.org/stable/c/197971e6ffc0a6356b2ba2b22beb42bc0f7e412dCNA: Linux
https://git.kernel.org/stable/c/3804e6de30ae7b053d53341d9d6944356cf23b40CNA: Linux
https://git.kernel.org/stable/c/717f721eb67d2dacd3ed5f7495aef2f442e84ce4CNA: Linux
https://git.kernel.org/stable/c/f73aa66dffcb8e61e78f01b56163ec16a15d06d2CNA: Linux
https://cert-portal.siemens.com/productcert/html/ssa-019113.htmlADP: siemens-SADP
https://cert-portal.siemens.com/productcert/html/ssa-457936.htmlADP: siemens-SADP
https://git.kernel.org/stable/c/197971e6ffc0a6356b2ba2b22beb42bc0f7e412d416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/1a02a5028bd6dead1f8503854ef3168d651cd417416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/3804e6de30ae7b053d53341d9d6944356cf23b40416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/3d3fcf23993bb756de2f912ab631cfdcc4746554416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/717f721eb67d2dacd3ed5f7495aef2f442e84ce4416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/99cde0a7b1e98fd3970aabef1300918e91698dd5416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/f73aa66dffcb8e61e78f01b56163ec16a15d06d2416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://cert-portal.siemens.com/productcert/html/ssa-019113.html0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
https://cert-portal.siemens.com/productcert/html/ssa-457936.html0b142b55-0307-4c5a-b3c9-f314f3fb7c5e

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