[PATCH 12/12] perf jitdump: Validate unwinding sizes against record payload

[Arnaldo Carvalho de Melo <acme@kernel.org>]

From: Arnaldo Carvalho de Melo <acme@redhat.com>

jit_repipe_unwinding_info() copies unwinding_size and eh_frame_hdr_size
from the jitdump record into jd-> fields without checking them against
the actual payload size.  Downstream, jit_add_eh_frame_info() in
genelf.c computes unwinding_table_size = unwinding_size -
eh_frame_hdr_size, which underflows when eh_frame_hdr_size >
unwinding_size.  The result is passed as d->d_size to libelf, causing
an OOB heap read into the output ELF file.

Validate that unwinding_size fits within the record payload and that
eh_frame_hdr_size does not exceed unwinding_size before allocating or
storing the values, so a bogus record cannot force a large allocation
that is then discarded.

mapped_size is likewise taken from the record and was narrowed into an
int for the mmap2 len computation in jit_repipe_code_load() and
jit_repipe_code_move(); values above INT_MAX would turn negative,
producing a wrong mmap2 length.  Use uint64_t for usize so the value
cannot truncate.

Fixes: 0284fecd13b6db3e ("perf jit: Add unwinding support")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Cc: Stefano Sanfilippo <ssanfilippo@chromium.org>
Cc: Stephane Eranian <eranian@google.com>
Assisted-by: Claude:claude-opus-4.6
Assisted-by: Opencode:mimo-v2.5-free
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/jitdump.c | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/jitdump.c b/tools/perf/util/jitdump.c
index 5f3a53f818c29f58..385c19b864aeee4c 100644
--- a/tools/perf/util/jitdump.c
+++ b/tools/perf/util/jitdump.c
@@ -462,7 +462,8 @@ static int jit_repipe_code_load(struct jit_buf_desc *jd, union jr_entry *jr)
 	u16 idr_size;
 	const char *sym;
 	uint64_t count;
-	int ret, csize, usize;
+	int ret, csize;
+	uint64_t usize;
 	pid_t nspid, pid, tid;
 	struct {
 		u32 pid, tid;
@@ -543,7 +544,7 @@ static int jit_repipe_code_load(struct jit_buf_desc *jd, union jr_entry *jr)
 
 	event->mmap2.pgoff = GEN_ELF_TEXT_OFFSET;
 	event->mmap2.start = addr;
-	event->mmap2.len   = usize ? ALIGN_8(csize) + usize : csize;
+	event->mmap2.len   = usize ? ALIGN_8((uint64_t)csize) + usize : (uint64_t)csize;
 	event->mmap2.pid   = pid;
 	event->mmap2.tid   = tid;
 	event->mmap2.ino   = st.st_ino;
@@ -612,7 +613,7 @@ static int jit_repipe_code_move(struct jit_buf_desc *jd, union jr_entry *jr)
 	char *filename;
 	size_t size;
 	struct stat st;
-	int usize;
+	uint64_t usize;
 	u16 idr_size;
 	int ret;
 	pid_t nspid, pid, tid;
@@ -761,6 +762,18 @@ jit_repipe_unwinding_info(struct jit_buf_desc *jd, union jr_entry *jr)
 		return -1;
 
 	unwinding_data_size  = jr->prefix.total_size - sizeof(jr->unwinding);
+
+	/*
+	 * Validate sizes before allocating — jit_add_eh_frame_info()
+	 * computes unwinding_size - eh_frame_hdr_size and uses the
+	 * result as a buffer length for libelf.
+	 */
+	if (jr->unwinding.unwinding_size > unwinding_data_size ||
+	    jr->unwinding.eh_frame_hdr_size > jr->unwinding.unwinding_size) {
+		pr_warning("jitdump: invalid unwinding sizes in unwinding_info record\n");
+		return -1;
+	}
+
 	unwinding_data = malloc(unwinding_data_size);
 	if (!unwinding_data)
 		return -1;
-- 
2.55.0