diff options
| author | Brahmajit Das <listout@listout.xyz> | 2025-10-02 00:47:38 +0530 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2025-10-01 13:53:20 -0700 |
| commit | 34904582b502a86fdb4d7984b12cacd2faabbe0d (patch) | |
| tree | 9d40b880dfbbea996dca87a6babae2fb02dad942 | |
| parent | 0c342bfc9949dffeaa83ebdde3b4b0ce59009348 (diff) | |
bpf: Skip scalar adjustment for BPF_NEG if dst is a pointer
In check_alu_op(), the verifier currently calls check_reg_arg() and
adjust_scalar_min_max_vals() unconditionally for BPF_NEG operations.
However, if the destination register holds a pointer, these scalar
adjustments are unnecessary and potentially incorrect.
This patch adds a check to skip the adjustment logic when the destination
register contains a pointer.
Reported-by: syzbot+d36d5ae81e1b0a53ef58@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=d36d5ae81e1b0a53ef58
Fixes: aced132599b3 ("bpf: Add range tracking for BPF_NEG")
Suggested-by: KaFai Wan <kafai.wan@linux.dev>
Suggested-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Brahmajit Das <listout@listout.xyz>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20251001191739.2323644-2-listout@listout.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
| -rw-r--r-- | kernel/bpf/verifier.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 73bba397672a..a5c52d53502a 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -15645,7 +15645,8 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn) } /* check dest operand */ - if (opcode == BPF_NEG) { + if (opcode == BPF_NEG && + regs[insn->dst_reg].type == SCALAR_VALUE) { err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK); err = err ?: adjust_scalar_min_max_vals(env, insn, ®s[insn->dst_reg], |