CVE-2025-38493

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 0 WARNING: CPU: 2 PID: 8153 at lib/string_helpers.c:1032 __fortify_report+0x55/0xa0 CPU: 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 to kernel_stack event structure), struct stack_entry marks its caller field with __counted_by(size). At the time of the memcpy, entry->size contains garbage from the ringbuffer, which under some circumstances is zero, triggering a kernel panic by buffer overflow.

Populate the size field before the memcpy so that the out-of-bounds check knows the correct size. This is analogous to __ftrace_trace_stack().

Weakness

The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.

Affected Software

Potential Mitigations

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/230.html
• https://cwe.mitre.org/data/definitions/231.html

References

• https://git.kernel.org/stable/c/7bb9ea515cda027c9e717e27fefcf34f092e7c41
• https://git.kernel.org/stable/c/823d798900481875ba6c68217af028c5ffd2976b
• https://git.kernel.org/stable/c/85a3bce695b361d85fc528e6fbb33e4c8089c806
• https://git.kernel.org/stable/c/fbf90f5aa7ac7cddc69148a71d58f12c8709ce2b