CVE - CVE-2024-55916

CVE-ID
CVE-2024-55916	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
Description
In the Linux kernel, the following vulnerability has been resolved: Drivers: hv: util: Avoid accessing a ringbuffer not initialized yet If the KVP (or VSS) daemon starts before the VMBus channel's ringbuffer is fully initialized, we can hit the panic below: hv_utils: Registering HyperV Utility Driver hv_vmbus: registering driver hv_utils ... BUG: kernel NULL pointer dereference, address: 0000000000000000 CPU: 44 UID: 0 PID: 2552 Comm: hv_kvp_daemon Tainted: G E 6.11.0-rc3+ #1 RIP: 0010:hv_pkt_iter_first+0x12/0xd0 Call Trace: ... vmbus_recvpacket hv_kvp_onchannelcallback vmbus_on_event tasklet_action_common tasklet_action handle_softirqs irq_exit_rcu sysvec_hyperv_stimer0 </IRQ> <TASK> asm_sysvec_hyperv_stimer0 ... kvp_register_done hvt_op_read vfs_read ksys_read __x64_sys_read This can happen because the KVP/VSS channel callback can be invoked even before the channel is fully opened: 1) as soon as hv_kvp_init() -> hvutil_transport_init() creates /dev/vmbus/hv_kvp, the kvp daemon can open the device file immediately and register itself to the driver by writing a message KVP_OP_REGISTER1 to the file (which is handled by kvp_on_msg() ->kvp_handle_handshake()) and reading the file for the driver's response, which is handled by hvt_op_read(), which calls hvt->on_read(), i.e. kvp_register_done(). 2) the problem with kvp_register_done() is that it can cause the channel callback to be called even before the channel is fully opened, and when the channel callback is starting to run, util_probe()-> vmbus_open() may have not initialized the ringbuffer yet, so the callback can hit the panic of NULL pointer dereference. To reproduce the panic consistently, we can add a "ssleep(10)" for KVP in __vmbus_open(), just before the first hv_ringbuffer_init(), and then we unload and reload the driver hv_utils, and run the daemon manually within the 10 seconds. Fix the panic by reordering the steps in util_probe() so the char dev entry used by the KVP or VSS daemon is not created until after vmbus_open() has completed. This reordering prevents the race condition from happening.
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/042253c57be901bfd19f15b68267442b70f510d5 URL:https://git.kernel.org/stable/c/042253c57be901bfd19f15b68267442b70f510d5 MISC:https://git.kernel.org/stable/c/07a756a49f4b4290b49ea46e089cbe6f79ff8d26 URL:https://git.kernel.org/stable/c/07a756a49f4b4290b49ea46e089cbe6f79ff8d26 MISC:https://git.kernel.org/stable/c/3dd7a30c6d7f90afcf19e9b072f572ba524d7ec6 URL:https://git.kernel.org/stable/c/3dd7a30c6d7f90afcf19e9b072f572ba524d7ec6 MISC:https://git.kernel.org/stable/c/718fe694a334be9d1a89eed22602369ac18d6583 URL:https://git.kernel.org/stable/c/718fe694a334be9d1a89eed22602369ac18d6583 MISC:https://git.kernel.org/stable/c/89fcec5e466b3ac9b376e0d621c71effa1a7983f URL:https://git.kernel.org/stable/c/89fcec5e466b3ac9b376e0d621c71effa1a7983f MISC:https://git.kernel.org/stable/c/d81f4e73aff9b861671df60e5100ad25cc16fbf8 URL:https://git.kernel.org/stable/c/d81f4e73aff9b861671df60e5100ad25cc16fbf8 MISC:https://git.kernel.org/stable/c/f091a224a2c82f1e302b1768d73bb6332f687321 URL:https://git.kernel.org/stable/c/f091a224a2c82f1e302b1768d73bb6332f687321
Assigning CNA
kernel.org
Date Record Created
20250109	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20250109)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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