From 9c74f0aab398cb32ab250401f323c0fdc9a3a496 Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Sun, 7 Jun 2026 21:05:15 -0300 Subject: [PATCH] perf symbols: Bounds-check .gnu_debuglink section data filename__read_debuglink() copies .gnu_debuglink section data into a caller-provided buffer via: strncpy(debuglink, data->d_buf, size); where size is PATH_MAX. If the ELF section is smaller than size and lacks a null terminator, strncpy reads past data->d_buf into adjacent memory. A malformed ELF file can trigger this, potentially causing a segfault or leaking heap data. Additionally, strncpy does not guarantee null termination when the source fills the buffer. Replace with an explicit memcpy bounded by both the output buffer size and the actual section data size (data->d_size), followed by explicit null termination. Fixes: e5a1845fc0aeca85 ("perf symbols: Split out util/symbol-elf.c") Reported-by: sashiko-bot Cc: Namhyung Kim Assisted-by: Claude:claude-opus-4.6 Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/symbol-elf.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c index 8fb25a5692b5..51e7cfe0f593 100644 --- a/tools/perf/util/symbol-elf.c +++ b/tools/perf/util/symbol-elf.c @@ -1027,7 +1027,14 @@ int filename__read_debuglink(const char *filename, char *debuglink, goto out_elf_end; /* the start of this section is a zero-terminated string */ - strncpy(debuglink, data->d_buf, size); + if (data->d_size > 0) { + size_t len = min(size - 1, data->d_size); + + memcpy(debuglink, data->d_buf, len); + debuglink[len] = '\0'; + } else { + debuglink[0] = '\0'; + } err = 0;