ghsa-hfvw-jf8h-qv56
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
m68k: Fix spinlock race in kernel thread creation
Context switching does take care to retain the correct lock owner across the switch from 'prev' to 'next' tasks. This does rely on interrupts remaining disabled for the entire duration of the switch.
This condition is guaranteed for normal process creation and context switching between already running processes, because both 'prev' and 'next' already have interrupts disabled in their saved copies of the status register.
The situation is different for newly created kernel threads. The status register is set to PS_S in copy_thread(), which does leave the IPL at 0. Upon restoring the 'next' thread's status register in switch_to() aka resume(), interrupts then become enabled prematurely. resume() then returns via ret_from_kernel_thread() and schedule_tail() where run queue lock is released (see finish_task_switch() and finish_lock_switch()).
A timer interrupt calling scheduler_tick() before the lock is released in finish_task_switch() will find the lock already taken, with the current task as lock owner. This causes a spinlock recursion warning as reported by Guenter Roeck.
As far as I can ascertain, this race has been opened in commit 533e6903bea0 ("m68k: split ret_from_fork(), simplify kernel_thread()") but I haven't done a detailed study of kernel history so it may well predate that commit.
Interrupts cannot be disabled in the saved status register copy for kernel threads (init will complain about interrupts disabled when finally starting user space). Disable interrupts temporarily when switching the tasks' register sets in resume().
Note that a simple oriw 0x700,%sr after restoring sr is not enough here - this leaves enough of a race for the 'spinlock recursion' warning to still be observed.
Tested on ARAnyM and qemu (Quadra 800 emulation).
{
"affected": [],
"aliases": [
"CVE-2024-38613"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-06-19T14:15:21Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nm68k: Fix spinlock race in kernel thread creation\n\nContext switching does take care to retain the correct lock owner across\nthe switch from \u0027prev\u0027 to \u0027next\u0027 tasks. This does rely on interrupts\nremaining disabled for the entire duration of the switch.\n\nThis condition is guaranteed for normal process creation and context\nswitching between already running processes, because both \u0027prev\u0027 and\n\u0027next\u0027 already have interrupts disabled in their saved copies of the\nstatus register.\n\nThe situation is different for newly created kernel threads. The status\nregister is set to PS_S in copy_thread(), which does leave the IPL at 0.\nUpon restoring the \u0027next\u0027 thread\u0027s status register in switch_to() aka\nresume(), interrupts then become enabled prematurely. resume() then\nreturns via ret_from_kernel_thread() and schedule_tail() where run queue\nlock is released (see finish_task_switch() and finish_lock_switch()).\n\nA timer interrupt calling scheduler_tick() before the lock is released\nin finish_task_switch() will find the lock already taken, with the\ncurrent task as lock owner. This causes a spinlock recursion warning as\nreported by Guenter Roeck.\n\nAs far as I can ascertain, this race has been opened in commit\n533e6903bea0 (\"m68k: split ret_from_fork(), simplify kernel_thread()\")\nbut I haven\u0027t done a detailed study of kernel history so it may well\npredate that commit.\n\nInterrupts cannot be disabled in the saved status register copy for\nkernel threads (init will complain about interrupts disabled when\nfinally starting user space). Disable interrupts temporarily when\nswitching the tasks\u0027 register sets in resume().\n\nNote that a simple oriw 0x700,%sr after restoring sr is not enough here\n- this leaves enough of a race for the \u0027spinlock recursion\u0027 warning to\nstill be observed.\n\nTested on ARAnyM and qemu (Quadra 800 emulation).",
"id": "GHSA-hfvw-jf8h-qv56",
"modified": "2024-06-19T15:30:54Z",
"published": "2024-06-19T15:30:54Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-38613"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0d9ae1253535f6e85a016e09c25ecbe6f7f59ef0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2a8d1d95302c7d52c6ac8fa5cb4a6948ae0d3a14"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4eeffecc8e3cce25bb559502c2fd94a948bcde82"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5213cc01d0464c011fdc09f318705603ed3a746b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/77b2b67a0f8bce260c53907e5749d61466d90c87"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/95f00caf767b5968c2c51083957b38be4748a78a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/da89ce46f02470ef08f0f580755d14d547da59ed"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f1d4274a84c069be0f6098ab10c3443fc1f7134c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f3baf0f4f92af32943ebf27b960e0552c6c082fd"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
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