[PATCH 5/5] perf dso: Replace assert with runtime check in dso__read_symbol()

From: Arnaldo Carvalho de Melo <[email protected]>

dso__read_symbol() asserts that len <= jited_prog_len, where len comes
from sym->end - sym->start (parsed from PERF_RECORD_KSYMBOL in
perf.data).  Both values originate from untrusted file input.

With NDEBUG (production builds), the assert is compiled out, allowing
an out-of-bounds heap read when the BPF program buffer is accessed.
Without NDEBUG, a crafted perf.data crashes perf with an assertion
failure.

Replace the assert with a runtime bounds check that returns NULL with
an appropriate error code, matching the existing error handling
pattern in this function.

Fixes: aa04707f507e ("perf dso: Support BPF programs in dso__read_symbol()")
Reported-by: sashiko-bot <[email protected]>
Cc: Ian Rogers <[email protected]>
Cc: Song Liu <[email protected]>
Assisted-by: Claude:claude-opus-4.6
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

Reviewed-by: Ian Rogers <[email protected]>
---
 tools/perf/util/dso.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 03e7f89d5465c91f..68cd90b5605f8c50 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -2033,7 +2033,12 @@ const u8 *dso__read_symbol(struct dso *dso, const char *symfs_filename,
 			errno = SYMBOL_ANNOTATE_ERRNO__BPF_MISSING_BTF;
 			return NULL;
 		}
-		assert(len <= info_linear->info.jited_prog_len);
+		if (len > info_linear->info.jited_prog_len) {
+			pr_debug("BPF symbol length %zu exceeds jited_prog_len %u\n",
+				 len, info_linear->info.jited_prog_len);
+			errno = SYMBOL_ANNOTATE_ERRNO__BPF_MISSING_BTF;
+			return NULL;
+		}
 		*out_buf_len = len;
 		return (const u8 *)(uintptr_t)(info_linear->info.jited_prog_insns);
 #else
-- 
2.55.0