tools/bpf_jit_disasm: Fix potential negative tpath index in get_exec_path()

If readlink() fails, len will be -1, which can cause negative indexing
and undefined behavior. This patch ensures that len is set to 0 on
readlink failure, preventing such issues.

Signed-off-by: Ruslan Semchenko <uncleruc2075@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20250612131816.1870-1-uncleruc2075@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/bpf/bpf_jit_disasm.c b/tools/bpf/bpf_jit_disasm.c
index 1baee9e2aba981ed701e5d0653a2ee026c0dc627..5ab8f80e2834abf7ec4b86af2beb22fd6985aeed 100644 (file)
--- a/tools/bpf/bpf_jit_disasm.c
+++ b/tools/bpf/bpf_jit_disasm.c
@@ -45,6 +45,8 @@ static void get_exec_path(char *tpath, size_t size)
        assert(path);
 
        len = readlink(path, tpath, size);
+       if (len < 0)
+               len = 0;
        tpath[len] = 0;
 
        free(path);