From 978fae9f1ac47e22890a1bd9ebf5fa46fe8b6ef7 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Mon, 29 Jul 2013 12:00:32 +0100 Subject: linux-user/signal.c: Avoid using uninitialized data in ARM sigreturn 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 Message-id: 1375095632-13735-3-git-send-email-peter.maydell@linaro.org Signed-off-by: Anthony Liguori --- linux-user/signal.c | 36 ++++++++++++++++++++---------------- 1 file changed, 20 insertions(+), 16 deletions(-) (limited to 'linux-user') 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; -- cgit v1.1