In the Linux kernel, the following vulnerability has been resolved: tracing: Save the event file…

Why it is Yellow

• CVSS 7.8 high
• On your watchlist: linux kernel

References

• https://git.kernel.org/stable/c/173914501b97236d7ea7dc2af7f30feddd4e1436
• https://git.kernel.org/stable/c/3609ada3c12cecfb0ae5ee82ef4f86c5f18a2dea
• https://git.kernel.org/stable/c/7a111ba0d1b74c99bc8f096565dc71945f694254
• https://git.kernel.org/stable/c/7cafc82e6153f05a221be678cd649d02e06ba909
• https://git.kernel.org/stable/c/8b307d64a60548e4a74cb746f74d7ed4bd49965e
• https://git.kernel.org/stable/c/9631dbccd3c649b567a5aafffea6b00634183997
• https://git.kernel.org/stable/c/a6165126b1a1b26342b55be6eb6ee23af8756aba
• https://git.kernel.org/stable/c/ac815a379644b2ad5008a009a3516ada31b5dd82

Original description

In the Linux kernel, the following vulnerability has been resolved: tracing: Save the event file instead of the compatible histogram create_field_var_hist() creates a histogram on the matched event to supply a field variable, and records it on the target so it can be torn down later: hist_data = find_compatible_hist(target_hist_data, file); ... /* Save the compatible histogram information */ var_hist->hist_data = hist_data; hist_data is not the histogram it creates. It is one that was already there, whose keys the new one copies. The saved pointer has a single user, unregister_field_var_hists(), which runs when the target is removed: file = hist_data->field_var_hists[i]->hist_data->event_file; find_compatible_hist() matches on keys alone, so it can pick one with no variables of its own. check_var_refs() then returns false and the user can remove it while the target still points at it: BUG: KASAN: slab-use-after-free in event_hist_trigger_free+0x2b2/0x320 Read of size 8 at addr ffff8880093b90e0 by task init/1 Freed by task 1: kfree+0x154/0x420 event_hist_trigger_free+0x1d5/0x320 event_hist_trigger_parse+0x35f3/0x69e0 trigger_process_regex+0x1a6/0x250 Save the event file instead. It is all the dereference ever wanted, and it does not go away when the user removes a trigger.