linux-kernel - [PATCH] libbpf: Fix integer overflow issue

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Message-ID: <20241007164648.20926-1-richard120310@gmail.com>
Date: Tue,  8 Oct 2024 00:46:48 +0800
From: I Hsin Cheng <richard120310@...il.com>
To: martin.lau@...ux.dev
Cc: ast@...nel.org,
	daniel@...earbox.net,
	andrii@...nel.org,
	eddyz87@...il.com,
	song@...nel.org,
	yonghong.song@...ux.dev,
	john.fastabend@...il.com,
	kpsingh@...nel.org,
	sdf@...ichev.me,
	haoluo@...gle.com,
	jolsa@...nel.org,
	bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	I Hsin Cheng <richard120310@...il.com>
Subject: [PATCH] libbpf: Fix integer overflow issue

Fix integer overflow issue discovered by coverity scan, where
"bpf_program_fd()" might return a value less than zero. Assignment of
"prog_fd" to "kern_data" will result in integer overflow in that case.

Do a pre-check after the program fd is returned, if it's negative we
should ignore this program and move on, or maybe add some error handling
mechanism here.

Signed-off-by: I Hsin Cheng <richard120310@...il.com>
---
 tools/lib/bpf/libbpf.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index a3be6f8fac09..95fb5e48e79e 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -8458,6 +8458,9 @@ static void bpf_map_prepare_vdata(const struct bpf_map *map)
 			continue;
 
 		prog_fd = bpf_program__fd(prog);
+		if (prog_fd < 0)
+			continue;
+
 		kern_data = st_ops->kern_vdata + st_ops->kern_func_off[i];
 		*(unsigned long *)kern_data = prog_fd;
 	}
-- 
2.43.0