perf machine: Check snprintf truncation for guest kallsyms path

machines__create_guest_kernel_maps() builds the guest kallsyms path
with snprintf() without checking the return value.  A truncated path
could pass the access() check if a prefix directory happens to contain
a file named "kallsyms", leading to the wrong file being used for
symbol resolution.

Check for truncation and skip the directory.

Fixes: a1645ce12a ("perf: 'perf kvm' tool for monitoring guest performance from host")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Cc: Zhang, Yanmin <yanmin_zhang@linux.intel.com>
Assisted-by: Claude:claude-opus-4.6
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
This commit is contained in:
Arnaldo Carvalho de Melo 2026-07-26 20:40:14 -03:00 • committed by Namhyung Kim
commit d04ef71492