From 983db9932a302f9e2ae1f1d4fd7c3149560bc269 Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Mon, 24 Apr 2023 10:37:12 +0200 Subject: [PATCH] x86: work around compiler diagnosing dangling pointer For quite come time print_insn() has been storing the address of a local variable into info->private_data. Since the compiler can't know that the field won't be accessed again after print_insn() returns, it may kind of legitimately diagnose this. And recent enough gcc does as of the introduction of the fetch_error() return paths (replacing setjmp()-based error handling). Utilizing that neither prefix_name() nor i386_dis_printf() actually use info->private_data, zap the pointer in fetch_error(), after having retrieved it for local use. --- opcodes/i386-dis.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/opcodes/i386-dis.c b/opcodes/i386-dis.c index f021bdaa3e7..fc0515cd2b0 100644 --- a/opcodes/i386-dis.c +++ b/opcodes/i386-dis.c @@ -345,6 +345,12 @@ fetch_error (const instr_info *ins) const struct dis_private *priv = ins->info->private_data; const char *name = NULL; + /* Our caller has put a pointer to a local variable in info->private_data + and it is going to return right after this function has returned. Some + compilers diagnose this as a dangling pointer. Zap the pointer here to + avoid needing to do so on all involved return paths in the caller. */ + ins->info->private_data = NULL; + if (ins->codep <= priv->the_buffer) return -1; -- 2.30.2