CVE-2025-38493 Information

Jul 29, 2025 cve

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 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 ( racing: 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().

Reference

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

CNNVD-202507-3469 (Published: 2025-07-28)

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