Skip to content
CVE PROGRAM SOURCE RECORD7.8 High

CVE-2023-52879

tracing: Have trace_event_file have ref counters

Read JSON ↗CVE.org ↗
Status
Published
Published
Updated
Assigning organization
Linux

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • e6807c873d8791ae5a5186ad05ec66cab926539a to < 961c4511c7578d6b8f39118be919016ec3db1c1eaffected
  • 407bf1c140f0757706c0b28604bcc90837d45ce2 to < a98172e36e5f1b3d29ad71fade2d611cfcc2fe6faffected
  • fa6d449e4d024d8c17f4288e0567d28ace69415c to < cbc7c29dff0fa18162f2a3889d82eeefd67305e0affected
  • a46bf337a20f9edd3c8041b025639842280d0575 to < 2fa74d29fc1899c237d51bf9a6e132ea5c488976affected
  • 9beec04370132a7a6cd1aa9897f6fffc6262ff28 to < 2c9de867ca285c397cd71af703763fe416265706affected
  • f5ca233e2e66dc1c249bf07eefa37e34a6c9346a to < 9034c87d61be8cff989017740a91701ac8195a1daffected
  • f5ca233e2e66dc1c249bf07eefa37e34a6c9346a to < bb32500fb9b78215e4ef6ee8b4345c5f5d7eafb4affected
  • 5.4.258 to < 5.4.262affected
  • 5.10.198 to < 5.10.202affected
  • 5.15.134 to < 5.15.140affected
  • 6.1.55 to < 6.1.64affected
  • 6.5.5 to < 6.5.13affected

Linux Linux

Default version status: affected

  • 6.6affected
  • 0 to < 6.6unaffected
  • 5.4.262 to ≤ 5.4.*unaffected
  • 5.10.202 to ≤ 5.10.*unaffected
  • 5.15.140 to ≤ 5.15.*unaffected
  • 6.1.64 to ≤ 6.1.*unaffected
  • 6.5.13 to ≤ 6.5.*unaffected
  • 6.6.1 to ≤ 6.6.*unaffected
  • 6.7 to ≤ *unaffected

References