CVE-2026-97557
Description
In the Linux kernel, the following vulnerability has been resolved: smb: client: avoid leaking refcount in cifs_queue_oplock_break() cifs_queue_oplock_break() unconditionally takes a reference on the target file before queueing cifs_oplock_break(). Only that work item decreases the reference counter again. If another oplock break arrives while that work is still queued, queue_work() will return false and not queue this second work item. As a result, we will never reach the point to drop the file reference again and are leaking this reference. This can be triggered when interacting with a slow-responding server. As a result, later unmount operations for this file system will fail with BUG: Dentry ... still in use (1) [unmount of cifs cifs] VFS: Busy inodes after unmount of cifs (cifs) kernel BUG at fs/super.c:777! Fix this by only incrementing the reference count if the work has been queued successfully. Taking it after queue_work() is safe because all three callers hold tcon->open_file_lock across the call and _cifsFileInfo_put() decrements under that same lock, so a worker that starts the handler in the window cannot drop the reference before it has been taken.
How to fix
- Linux Linux13b9519b19e6e58a6cd01e63062cd1da7bd6449a, 0fb92ac85db58945ad7b970ff17674001487b3a3, 735a3a610136ae10f381d0909dff38e5b5c5f056, de2a6bcff2659bea40c7485115b57f0ae189fc01, af0193bbf1ac8c0f67f972998b0cc629d6116cf6, 2ed2c29dd9593637cfa25ac1eb23241b20202778, dfe7b750c7e069873a8a57a11c816831a235618a, 9f2e63f1b2d5fc5b5423424902c091123e220e7e, 3.17, 4.10, 4.15, 4.20, 5.1 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| Linux Linux | b98749cac4a695f084a5ff076f4510b23e353ecd ≤ v < 13b9519b19e6e58a6cd01e63062cd1da7bd6449a, b98749cac4a695f084a5ff076f4510b23e353ecd ≤ v < 0fb92ac85db58945ad7b970ff17674001487b3a3, b98749cac4a695f084a5ff076f4510b23e353ecd ≤ v < 735a3a610136ae10f381d0909dff38e5b5c5f056, b98749cac4a695f084a5ff076f4510b23e353ecd ≤ v < de2a6bcff2659bea40c7485115b57f0ae189fc01, b98749cac4a695f084a5ff076f4510b23e353ecd ≤ v < af0193bbf1ac8c0f67f972998b0cc629d6116cf6, b98749cac4a695f084a5ff076f4510b23e353ecd ≤ v < 2ed2c29dd9593637cfa25ac1eb23241b20202778, b98749cac4a695f084a5ff076f4510b23e353ecd ≤ v < dfe7b750c7e069873a8a57a11c816831a235618a, b98749cac4a695f084a5ff076f4510b23e353ecd ≤ v < 9f2e63f1b2d5fc5b5423424902c091123e220e7e, 2429fcf06d3cb962693868ab0a927c9038f12a2d, 1ee4f2d7cdcd4508cc3cbe3b2622d7177b89da12, 53fc31a4853e30d6e8f142b824f724da27ff3e40, 8092ecc306d81186a64cda42411121f4d35aaff4, ebac4d0adf68f8962bd82fcf483936edd6ec095b, 3.16.72 ≤ v < 3.17, 4.9.171 ≤ v < 4.10, 4.14.114 ≤ v < 4.15, 4.19.37 ≤ v < 4.20, 5.0.10 ≤ v < 5.1, 5.1 | 13b9519b19e6e58a6cd01e63062cd1da7bd6449a, 0fb92ac85db58945ad7b970ff17674001487b3a3, 735a3a610136ae10f381d0909dff38e5b5c5f056, de2a6bcff2659bea40c7485115b57f0ae189fc01, af0193bbf1ac8c0f67f972998b0cc629d6116cf6, 2ed2c29dd9593637cfa25ac1eb23241b20202778, dfe7b750c7e069873a8a57a11c816831a235618a, 9f2e63f1b2d5fc5b5423424902c091123e220e7e, 3.17, 4.10, 4.15, 4.20, 5.1 |
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