ksmbd: fix null pointer dereference in proc_show_files()

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Summary

CVECVE-2026-64140
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-19 16:17:55 UTC
Updated2026-07-19 16:17:55 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ksmbd: fix null pointer dereference in proc_show_files() When a SMB2 client opens a file with a durable v2 handle and then issues SMB2 SESSION_LOGOFF, session_fd_check() clears fp->tcon = NULL on the reconnectable file pointer but leaves the fp registered in global_ft.idr until the durable scavenger fires (up to fp->durable_timeout seconds later). During that window any read of /proc/fs/ksmbd/files (mode 0400) panics the kernel because proc_show_files() walks global_ft.idr and unconditionally dereferences fp->tcon->id with no NULL guard. Reproducer requires only a successful SMB2 SESSION_SETUP and a share configured with 'durable handles = yes'. KASAN report on mainline 70390501d194: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: 0010:proc_show_files+0x118/0x740 Call Trace: proc_show_files+0x118/0x740 seq_read_iter+0x4ef/0xe10 proc_reg_read_iter+0x1b7/0x280 ... Guard the dereference. A durable-disconnected fp legitimately has no tcon; report its tree id as 0 rather than oopsing.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected b38f99c1217ae04753340f0fdcd8f35bf56841dc 8eab081627b67216d1c8f638b68289b500dc9a6b git Not specified
CNA Linux Linux affected b38f99c1217ae04753340f0fdcd8f35bf56841dc 904901561e61a2b559070b20c74a8c95491f30aa git Not specified
CNA Linux Linux affected 7.0 Not specified
CNA Linux Linux unaffected 7.0 semver Not specified
CNA Linux Linux unaffected 7.0.11 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/904901561e61a2b559070b20c74a8c95491f30aa 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8eab081627b67216d1c8f638b68289b500dc9a6b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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