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Message-Id: <20250505230624.2692522-202-sashal@kernel.org>
Date: Mon, 5 May 2025 19:06:14 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
stable@...r.kernel.org
Cc: Viktor Malik <vmalik@...hat.com>,
Andrii Nakryiko <andrii@...nel.org>,
Quentin Monnet <qmo@...nel.org>,
Alexei Starovoitov <ast@...nel.org>,
Sasha Levin <sashal@...nel.org>,
daniel@...earbox.net,
bpf@...r.kernel.org
Subject: [PATCH AUTOSEL 6.1 202/212] bpftool: Fix readlink usage in get_fd_type
From: Viktor Malik <vmalik@...hat.com>
[ Upstream commit 0053f7d39d491b6138d7c526876d13885cbb65f1 ]
The `readlink(path, buf, sizeof(buf))` call reads at most sizeof(buf)
bytes and *does not* append null-terminator to buf. With respect to
that, fix two pieces in get_fd_type:
1. Change the truncation check to contain sizeof(buf) rather than
sizeof(path).
2. Append null-terminator to buf.
Reported by Coverity.
Signed-off-by: Viktor Malik <vmalik@...hat.com>
Signed-off-by: Andrii Nakryiko <andrii@...nel.org>
Reviewed-by: Quentin Monnet <qmo@...nel.org>
Link: https://lore.kernel.org/bpf/20250129071857.75182-1-vmalik@redhat.com
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
tools/bpf/bpftool/common.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
index db02b000fbebd..eea00bc15b5cc 100644
--- a/tools/bpf/bpftool/common.c
+++ b/tools/bpf/bpftool/common.c
@@ -384,10 +384,11 @@ int get_fd_type(int fd)
p_err("can't read link type: %s", strerror(errno));
return -1;
}
- if (n == sizeof(path)) {
+ if (n == sizeof(buf)) {
p_err("can't read link type: path too long!");
return -1;
}
+ buf[n] = '\0';
if (strstr(buf, "bpf-map"))
return BPF_OBJ_MAP;
--
2.39.5
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