2.1 KiB
CVE-2025-38493
Description
In the Linux kernel, the following vulnerability has been resolved:tracing/osnoise: Fix crash in timerlat_dump_stack()We have observed kernel panics when using timerlat with stack saving,with the following dmesg output:memcpy: detected buffer overflow: 88 byte write of buffer size 0WARNING: CPU: 2 PID: 8153 at lib/string_helpers.c:1032 __fortify_report+0x55/0xa0CPU: 2 UID: 0 PID: 8153 Comm: timerlatu/2 Kdump: loaded Not tainted 6.15.3-200.fc42.x86_64 #1 PREEMPT(lazy)Call Trace: ? trace_buffer_lock_reserve+0x2a/0x60 __fortify_panic+0xd/0xf __timerlat_dump_stack.cold+0xd/0xd timerlat_dump_stack.part.0+0x47/0x80 timerlat_fd_read+0x36d/0x390 vfs_read+0xe2/0x390 ? syscall_exit_to_user_mode+0x1d5/0x210 ksys_read+0x73/0xe0 do_syscall_64+0x7b/0x160 ? exc_page_fault+0x7e/0x1a0 entry_SYSCALL_64_after_hwframe+0x76/0x7e__timerlat_dump_stack() constructs the ftrace stack entry like this:struct stack_entry *entry;...memcpy(&entry->caller, fstack->calls, size);entry->size = fstack->nr_entries;Since commit e7186af7fb26 ("tracing: Add back FORTIFY_SOURCE logic tokernel_stack event structure"), struct stack_entry marks its callerfield with __counted_by(size). At the time of the memcpy, entry->sizecontains garbage from the ringbuffer, which under some circumstances iszero, triggering a kernel panic by buffer overflow.Populate the size field before the memcpy so that the out-of-boundscheck knows the correct size. This is analogous to__ftrace_trace_stack().
POC
Reference
No PoCs from references.