Rephrase code used in ARM sigreturn functions to avoid using
uninitialized variables. This fixes one genuine problem ('frame'
would not be initialized if we took the error-exit path because
our stackpointer was misaligned) and one which is clang being
alarmist (frame_addr wouldn't be initialized, though this is
harmless since unlock_user_struct ignores its second argument
in these cases; however since we don't generally make use of
this not-really-documented effect it's better avoided).
Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
---
linux-user/signal.c | 36 ++++++++++++++++++++----------------
1 file changed, 20 insertions(+), 16 deletions(-)
diff --git a/linux-user/signal.c b/linux-user/signal.c
index d63777d..23d65da 100644
--- a/linux-user/signal.c
+++ b/linux-user/signal.c
@@ -1552,7 +1552,7 @@ restore_sigcontext(CPUARMState *env, struct
target_sigcontext *sc)
static long do_sigreturn_v1(CPUARMState *env)
{
abi_ulong frame_addr;
- struct sigframe_v1 *frame;
+ struct sigframe_v1 *frame = NULL;
target_sigset_t set;
sigset_t host_set;
int i;
@@ -1562,10 +1562,11 @@ static long do_sigreturn_v1(CPUARMState *env)
* then 'sp' should be word aligned here. If it's
* not, then the user is trying to mess with us.
*/
- if (env->regs[13] & 7)
- goto badframe;
-
frame_addr = env->regs[13];
+ if (frame_addr & 7) {
+ goto badframe;
+ }
+
if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1))
goto badframe;
@@ -1693,17 +1694,18 @@ static int do_sigframe_return_v2(CPUARMState *env,
target_ulong frame_addr,
static long do_sigreturn_v2(CPUARMState *env)
{
abi_ulong frame_addr;
- struct sigframe_v2 *frame;
+ struct sigframe_v2 *frame = NULL;
/*
* Since we stacked the signal on a 64-bit boundary,
* then 'sp' should be word aligned here. If it's
* not, then the user is trying to mess with us.
*/
- if (env->regs[13] & 7)
- goto badframe;
-
frame_addr = env->regs[13];
+ if (frame_addr & 7) {
+ goto badframe;
+ }
+
if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1))
goto badframe;
@@ -1731,7 +1733,7 @@ long do_sigreturn(CPUARMState *env)
static long do_rt_sigreturn_v1(CPUARMState *env)
{
abi_ulong frame_addr;
- struct rt_sigframe_v1 *frame;
+ struct rt_sigframe_v1 *frame = NULL;
sigset_t host_set;
/*
@@ -1739,10 +1741,11 @@ static long do_rt_sigreturn_v1(CPUARMState *env)
* then 'sp' should be word aligned here. If it's
* not, then the user is trying to mess with us.
*/
- if (env->regs[13] & 7)
- goto badframe;
-
frame_addr = env->regs[13];
+ if (frame_addr & 7) {
+ goto badframe;
+ }
+
if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1))
goto badframe;
@@ -1772,17 +1775,18 @@ badframe:
static long do_rt_sigreturn_v2(CPUARMState *env)
{
abi_ulong frame_addr;
- struct rt_sigframe_v2 *frame;
+ struct rt_sigframe_v2 *frame = NULL;
/*
* Since we stacked the signal on a 64-bit boundary,
* then 'sp' should be word aligned here. If it's
* not, then the user is trying to mess with us.
*/
- if (env->regs[13] & 7)
- goto badframe;
-
frame_addr = env->regs[13];
+ if (frame_addr & 7) {
+ goto badframe;
+ }
+
if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1))
goto badframe;
--
1.7.9.5
