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CVE PROGRAM SOURCE RECORD7.5 High

CVE-2026-98173

smb: client: fix use-after-free of iface in cifs_try_adding_channels()

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix use-after-free of iface in cifs_try_adding_channels() cifs_try_adding_channels() iterates ses->iface_list with list_for_each_entry_safe_from(), which captures the next entry (niface) under iface_lock. The loop body then drops iface_lock for the whole duration of cifs_ses_add_channel(). A concurrent interface refresh (SMB3_request_interfaces() -> parse_server_interfaces()) marks all ifaces inactive and removes and frees any that are not re-advertised via list_del() + kref_put(), where release_iface() is a bare kfree(). Since niface typically has no channel holding a reference, the list reference is its last and it can be freed inside the unlocked window. On continue, the iterator advance step then dereferences niface->iface_head.next, and the loop body reads iface->rdma_capable/is_active, both on freed memory. Fix this by never keeping an unreferenced list pointer across the unlocked window. Each channel attempt now re-scans the list from the head under iface_lock, takes a kref on the selected candidate, and passes only that referenced candidate to cifs_ses_add_channel(). weight_fulfilled still tracks selection progress, so restarting the scan preserves the original weighted distribution and the weight_fulfilled-before-kref_put ordering on the failure path. Add a per-pass attempts cap so a flapping interface refresh cannot keep the inner loop spinning within a single tries increment.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • aa45dadd34e44fcd6a9df4b395bee5b5633b4cec to < ee0d8f83d68f6e6509f092c997ccab3c8c801538affected
  • aa45dadd34e44fcd6a9df4b395bee5b5633b4cec to < c941f1ebfd26f683de81091473f3596a218abff0affected
  • aa45dadd34e44fcd6a9df4b395bee5b5633b4cec to < e99040e5e9c60441e6b4725e1a7b88c3106ae903affected
  • aa45dadd34e44fcd6a9df4b395bee5b5633b4cec to < ec36b38e65596950e6c29bed7dfc90b98707c19caffected
  • aa45dadd34e44fcd6a9df4b395bee5b5633b4cec to < d034e836eefd7ce75e588f7031cffbeec594f5acaffected

Linux Linux

Default version status: affected

  • 5.19affected
  • 0 to < 5.19unaffected
  • 6.6.160 to ≤ 6.6.*unaffected
  • 6.12.112 to ≤ 6.12.*unaffected
  • 6.18.54 to ≤ 6.18.*unaffected
  • 7.2.8 to ≤ 7.2.*unaffected
  • 7.3 to ≤ *unaffected

References