[PATCH 02/12] perf jitdump: Validate code_size against total_size in code load

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

jit_repipe_code_load() reads code_size from the jitdump record and uses
it to compute a pointer to the code blob:

  code = (unsigned long)jr + jr->load.p.total_size - csize;

An oversized code_size underflows the pointer arithmetic, causing OOB
reads into earlier heap memory.  Validate that code_size fits within the
record (total_size - sizeof(jr->load)) before the pointer computation.

code_size is uint64_t but csize is int; values above INT_MAX wrap
negative when narrowed into csize, which defeats the bounds check and
sends the code pointer past the end of the record.  Reject those too.

Fixes: 9b07e27f88b9 ("perf inject: Add jitdump mmap injection support")
Reported-by: sashiko-bot <[email protected]>
Cc: Stephane Eranian <[email protected]>
Assisted-by: Claude:claude-opus-4.6
Assisted-by: Opencode:mimo-v2.5-free
Reviewed-by: Ian Rogers <[email protected]>
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
---
 tools/perf/util/jitdump.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tools/perf/util/jitdump.c b/tools/perf/util/jitdump.c
index 4b7c7ba7cd95ddbb..3195f94187164066 100644
--- a/tools/perf/util/jitdump.c
+++ b/tools/perf/util/jitdump.c
@@ -9,6 +9,7 @@
 #include <fcntl.h>
 #include <unistd.h>
 #include <inttypes.h>
+#include <limits.h>
 #include <byteswap.h>
 #include <sys/stat.h>
 #include <sys/mman.h>
@@ -450,6 +451,16 @@ static int jit_repipe_code_load(struct jit_buf_desc *jd, union jr_entry *jr)
 	csize = jr->load.code_size;
 	usize = jd->unwinding_mapped_size;
 	addr  = jr->load.code_addr;
+
+	/* code blob lives at the end of the record, validate it fits */
+	if (jr->load.p.total_size < sizeof(jr->load) ||
+	    jr->load.code_size > jr->load.p.total_size - sizeof(jr->load) ||
+	    jr->load.code_size > INT_MAX) {
+		pr_warning("jitdump: invalid code_size %" PRIu64 " (total_size=%u) in code_load record\n",
+			   (uint64_t)jr->load.code_size, jr->load.p.total_size);
+		return -1;
+	}
+
 	sym   = (void *)((unsigned long)jr + sizeof(jr->load));
 	code  = (unsigned long)jr + jr->load.p.total_size - csize;
 	count = jr->load.code_index;
-- 
2.55.0