CVE-2024-40915 Affecting linux-6.1 package, versions <6.1.119-1~deb11u1
Threat Intelligence
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Test your applications- Snyk IDSNYK-DEBIAN11-LINUX61-8601190
- published2 Jan 2025
- disclosed12 Jul 2024
Introduced: 12 Jul 2024
CVE-2024-40915 (opens in a new tab)How to fix?
Upgrade Debian:11 linux-6.1 to version 6.1.119-1~deb11u1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream linux-6.1 package and not the linux-6.1 package as distributed by Debian.
See How to fix? for Debian:11 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
riscv: rewrite __kernel_map_pages() to fix sleeping in invalid context
__kernel_map_pages() is a debug function which clears the valid bit in page table entry for deallocated pages to detect illegal memory accesses to freed pages.
This function set/clear the valid bit using __set_memory(). __set_memory() acquires init_mm's semaphore, and this operation may sleep. This is problematic, because __kernel_map_pages() can be called in atomic context, and thus is illegal to sleep. An example warning that this causes:
BUG: sleeping function called from invalid context at kernel/locking/rwsem.c:1578 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 2, name: kthreadd preempt_count: 2, expected: 0 CPU: 0 PID: 2 Comm: kthreadd Not tainted 6.9.0-g1d4c6d784ef6 #37 Hardware name: riscv-virtio,qemu (DT) Call Trace: [<ffffffff800060dc>] dump_backtrace+0x1c/0x24 [<ffffffff8091ef6e>] show_stack+0x2c/0x38 [<ffffffff8092baf8>] dump_stack_lvl+0x5a/0x72 [<ffffffff8092bb24>] dump_stack+0x14/0x1c [<ffffffff8003b7ac>] __might_resched+0x104/0x10e [<ffffffff8003b7f4>] __might_sleep+0x3e/0x62 [<ffffffff8093276a>] down_write+0x20/0x72 [<ffffffff8000cf00>] __set_memory+0x82/0x2fa [<ffffffff8000d324>] __kernel_map_pages+0x5a/0xd4 [<ffffffff80196cca>] __alloc_pages_bulk+0x3b2/0x43a [<ffffffff8018ee82>] __vmalloc_node_range+0x196/0x6ba [<ffffffff80011904>] copy_process+0x72c/0x17ec [<ffffffff80012ab4>] kernel_clone+0x60/0x2fe [<ffffffff80012f62>] kernel_thread+0x82/0xa0 [<ffffffff8003552c>] kthreadd+0x14a/0x1be [<ffffffff809357de>] ret_from_fork+0xe/0x1c
Rewrite this function with apply_to_existing_page_range(). It is fine to not have any locking, because __kernel_map_pages() works with pages being allocated/deallocated and those pages are not changed by anyone else in the meantime.
References
- https://security-tracker.debian.org/tracker/CVE-2024-40915
- https://git.kernel.org/stable/c/8661a7af04991201640863ad1a0983173f84b5eb
- https://git.kernel.org/stable/c/919f8626099d9909b9a9620b05e8c8ab06581876
- https://git.kernel.org/stable/c/d5257ceb19d92069195254866421f425aea42915
- https://git.kernel.org/stable/c/fb1cf0878328fe75d47f0aed0a65b30126fcefc4