Description
In the Linux kernel, the following vulnerability has been resolved: refscale: Fix uninitalized use of wait_queue_head_t Running the refscale test occasionally crashes the kernel with the following error: [ 8569.952896] BUG: unable to handle page fault for address: ffffffffffffffe8 [ 8569.952900] #PF: supervisor read access in kernel mode [ 8569.952902] #PF: error_code(0x0000) - not-present page [ 8569.952904] PGD c4b048067 P4D c4b049067 PUD c4b04b067 PMD 0 [ 8569.952910] Oops: 0000 [#1] PREEMPT_RT SMP NOPTI [ 8569.952916] Hardware name: Dell Inc. PowerEdge R750/0WMWCR, BIOS 1.2.4 05/28/2021 [ 8569.952917] RIP: 0010:prepare_to_wait_event+0x101/0x190 : [ 8569.952940] Call Trace: [ 8569.952941] <TASK> [ 8569.952944] ref_scale_reader+0x380/0x4a0 [refscale] [ 8569.952959] kthread+0x10e/0x130 [ 8569.952966] ret_from_fork+0x1f/0x30 [ 8569.952973] </TASK> The likely cause is that init_waitqueue_head() is called after the call to the torture_create_kthread() function that creates the ref_scale_reader kthread. Although this init_waitqueue_head() call will very likely complete before this kthread is created and starts running, it is possible that the calling kthread will be delayed between the calls to torture_create_kthread() and init_waitqueue_head(). In this case, the new kthread will use the waitqueue head before it is properly initialized, which is not good for the kernel's health and well-being. The above crash happened here: static inline void __add_wait_queue(...) { : if (!(wq->flags & WQ_FLAG_PRIORITY)) <=== Crash here The offset of flags from list_head entry in wait_queue_entry is -0x18. If reader_tasks[i].wq.head.next is NULL as allocated reader_task structure is zero initialized, the instruction will try to access address 0xffffffffffffffe8, which is exactly the fault address listed above. This commit therefore invokes init_waitqueue_head() before creating the kthread.
Product status
653ed64b01dc5989f8f579d0038e987476c2c023 (git) before 066fbd8bc981cf49923bf828b7b4092894df577f
653ed64b01dc5989f8f579d0038e987476c2c023 (git) before ec9d118ad99dc6f1bc674c1e649c25533d89b9ba
653ed64b01dc5989f8f579d0038e987476c2c023 (git) before e0322a255a2242dbe4686b6176b3c83dea490529
653ed64b01dc5989f8f579d0038e987476c2c023 (git) before e5de968a9032366198720eac4f368ed7e690b3ef
653ed64b01dc5989f8f579d0038e987476c2c023 (git) before 70a2856fd1d0a040c876ba9e3f89b949ae92e4dd
653ed64b01dc5989f8f579d0038e987476c2c023 (git) before f5063e8948dad7f31adb007284a5d5038ae31bb8
5.9
Any version before 5.9
5.10.195 (semver)
5.15.132 (semver)
6.1.53 (semver)
6.4.16 (semver)
6.5.3 (semver)
6.6 (original_commit_for_fix)
References
git.kernel.org/...c/066fbd8bc981cf49923bf828b7b4092894df577f
git.kernel.org/...c/ec9d118ad99dc6f1bc674c1e649c25533d89b9ba
git.kernel.org/...c/e0322a255a2242dbe4686b6176b3c83dea490529
git.kernel.org/...c/e5de968a9032366198720eac4f368ed7e690b3ef
git.kernel.org/...c/70a2856fd1d0a040c876ba9e3f89b949ae92e4dd
git.kernel.org/...c/f5063e8948dad7f31adb007284a5d5038ae31bb8
Data based on CVE®. Copyright © 1999-2025, The MITRE Corporation. All rights reserved.