bpf: Fix bounds for bpf_prog_get_file_line linfo loop

We may overrun the bounds because linfo and jited_linfo are already
advanced to prog->aux->linfo_idx, hence we must only iterate the
remaining elements until we reach prog->aux->nr_linfo. Adjust the
nr_linfo calculation to fix this. Reported in [0].

  [0]: https://lore.kernel.org/bpf/f3527af3b0620ce36e299e97e7532d2555018de2.camel@gmail.com

Reported-by: Eduard Zingerman <eddyz87@gmail.com>
Fixes: 0e521efaf363 ("bpf: Add function to extract program source info")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250705053035.3020320-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index fe8a53f3c5bc4190195dd911091b00fb7d0dd67a..61613785bdd0f53f444f5fe2f3544ba4aed8e126 100644 (file)
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -3244,6 +3244,7 @@ int bpf_prog_get_file_line(struct bpf_prog *prog, unsigned long ip, const char *
        struct bpf_line_info *linfo;
        void **jited_linfo;
        struct btf *btf;
+       int nr_linfo;
 
        btf = prog->aux->btf;
        linfo = prog->aux->linfo;
@@ -3258,8 +3259,9 @@ int bpf_prog_get_file_line(struct bpf_prog *prog, unsigned long ip, const char *
 
        insn_start = linfo[0].insn_off;
        insn_end = insn_start + len;
+       nr_linfo = prog->aux->nr_linfo - prog->aux->linfo_idx;
 
-       for (int i = 0; i < prog->aux->nr_linfo &&
+       for (int i = 0; i < nr_linfo &&
             linfo[i].insn_off >= insn_start && linfo[i].insn_off < insn_end; i++) {
                if (jited_linfo[i] >= (void *)ip)
                        break;