linux-kernel - Silence compiler warning in arch/x86/kvm/emulate.c

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Sat, 29 Aug 2015 17:49:16 -0400
From:	Valdis Kletnieks <Valdis.Kletnieks@...edu>
To:	Gleb Natapov <gleb@...nel.org>, Paolo Bonzini <pbonzini@...hat.com>
cc:	x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Aruna Hewapathirane <aruna.hewapathirane@...il.com>
Subject: Silence compiler warning in  arch/x86/kvm/emulate.c

Compiler warning:

 CC [M]  arch/x86/kvm/emulate.o
arch/x86/kvm/emulate.c: In function "__do_insn_fetch_bytes":
arch/x86/kvm/emulate.c:814:9: warning: "linear" may be used uninitialized in this function [-Wmaybe-uninitialized]

GCC is smart enough to realize that the inlined __linearize may return before
setting the value of linear, but not smart enough to realize the same
X86EMU_CONTINUE blocks actual use of the value.  However, the value of
'linear' can only be set to one value, so hoisting the one line of code
upwards makes GCC happy with the code.

Reported-by: Aruna Hewapathirane <aruna.hewapathirane@...il.com>
Tested-by: Aruna Hewapathirane <aruna.hewapathirane@...il.com>
Signed-off-by: Valdis Kletnieks <valdis.kletnieks@...edu>

--- a/arch/x86/kvm/emulate.c.dist	2015-08-11 14:10:05.366061993 -0400
+++ b/arch/x86/kvm/emulate.c	2015-08-29 13:43:13.014163958 -0400
@@ -650,6 +650,7 @@ static __always_inline int __linearize(s
 	u16 sel;
 
 	la = seg_base(ctxt, addr.seg) + addr.ea;
+	*linear = la;
 	*max_size = 0;
 	switch (mode) {
 	case X86EMUL_MODE_PROT64:
@@ -693,7 +694,6 @@ static __always_inline int __linearize(s
 	}
 	if (insn_aligned(ctxt, size) && ((la & (size - 1)) != 0))
 		return emulate_gp(ctxt, 0);
-	*linear = la;
 	return X86EMUL_CONTINUE;
 bad:
 	if (addr.seg == VCPU_SREG_SS)

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/