CVE - CVE-2023-52879

CVE-ID
CVE-2023-52879	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: tracing: Have trace_event_file have ref counters The following can crash the kernel: # cd /sys/kernel/tracing # echo 'p:sched schedule' > kprobe_events # exec 5>>events/kprobes/sched/enable # > kprobe_events # exec 5>&- The above commands: 1. Change directory to the tracefs directory 2. Create a kprobe event (doesn't matter what one) 3. Open bash file descriptor 5 on the enable file of the kprobe event 4. Delete the kprobe event (removes the files too) 5. Close the bash file descriptor 5 The above causes a crash! BUG: kernel NULL pointer dereference, address: 0000000000000028 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 6 PID: 877 Comm: bash Not tainted 6.5.0-rc4-test-00008-g2c6b6b1029d4-dirty #186 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 RIP: 0010:tracing_release_file_tr+0xc/0x50 What happens here is that the kprobe event creates a trace_event_file "file" descriptor that represents the file in tracefs to the event. It maintains state of the event (is it enabled for the given instance?). Opening the "enable" file gets a reference to the event "file" descriptor via the open file descriptor. When the kprobe event is deleted, the file is also deleted from the tracefs system which also frees the event "file" descriptor. But as the tracefs file is still opened by user space, it will not be totally removed until the final dput() is called on it. But this is not true with the event "file" descriptor that is already freed. If the user does a write to or simply closes the file descriptor it will reference the event "file" descriptor that was just freed, causing a use-after-free bug. To solve this, add a ref count to the event "file" descriptor as well as a new flag called "FREED". The "file" will not be freed until the last reference is released. But the FREE flag will be set when the event is removed to prevent any more modifications to that event from happening, even if there's still a reference to the event "file" descriptor.
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/2c9de867ca285c397cd71af703763fe416265706 URL:https://git.kernel.org/stable/c/2c9de867ca285c397cd71af703763fe416265706 MISC:https://git.kernel.org/stable/c/2fa74d29fc1899c237d51bf9a6e132ea5c488976 URL:https://git.kernel.org/stable/c/2fa74d29fc1899c237d51bf9a6e132ea5c488976 MISC:https://git.kernel.org/stable/c/9034c87d61be8cff989017740a91701ac8195a1d URL:https://git.kernel.org/stable/c/9034c87d61be8cff989017740a91701ac8195a1d MISC:https://git.kernel.org/stable/c/961c4511c7578d6b8f39118be919016ec3db1c1e URL:https://git.kernel.org/stable/c/961c4511c7578d6b8f39118be919016ec3db1c1e MISC:https://git.kernel.org/stable/c/a98172e36e5f1b3d29ad71fade2d611cfcc2fe6f URL:https://git.kernel.org/stable/c/a98172e36e5f1b3d29ad71fade2d611cfcc2fe6f MISC:https://git.kernel.org/stable/c/bb32500fb9b78215e4ef6ee8b4345c5f5d7eafb4 URL:https://git.kernel.org/stable/c/bb32500fb9b78215e4ef6ee8b4345c5f5d7eafb4 MISC:https://git.kernel.org/stable/c/cbc7c29dff0fa18162f2a3889d82eeefd67305e0 URL:https://git.kernel.org/stable/c/cbc7c29dff0fa18162f2a3889d82eeefd67305e0
Assigning CNA
kernel.org
Date Record Created
20240521	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 (20240521)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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