From 5f4ad04a1e805d14de080ff9d5384b4d20518a9a Mon Sep 17 00:00:00 2001 From: Al Viro Date: Mon, 20 Sep 2010 15:13:09 +0100 Subject: [PATCH] frv: fix address verification holes in setup_frame/setup_rt_frame a) sa_handler might be maliciously set to point to kernel memory; blindly dereferencing it in FDPIC case is a Bad Idea(tm). b) I'm not sure you need that set_fs(USER_DS) there at all, but if you do, you'd better do it *before* checking the frame you've decided to use with access_ok(), lest sigaltstack() becomes a convenient roothole. Signed-off-by: Al Viro Signed-off-by: David Howells Signed-off-by: Linus Torvalds --- arch/frv/kernel/signal.c | 38 ++++++++++++++++++++++---------------- 1 file changed, 22 insertions(+), 16 deletions(-) diff --git a/arch/frv/kernel/signal.c b/arch/frv/kernel/signal.c index 7fc29615ef0..5fb2d0661c7 100644 --- a/arch/frv/kernel/signal.c +++ b/arch/frv/kernel/signal.c @@ -253,6 +253,8 @@ static int setup_frame(int sig, struct k_sigaction *ka, sigset_t *set) struct sigframe __user *frame; int rsig; + set_fs(USER_DS); + frame = get_sigframe(ka, sizeof(*frame)); if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) @@ -296,22 +298,23 @@ static int setup_frame(int sig, struct k_sigaction *ka, sigset_t *set) (unsigned long) (frame->retcode + 2)); } - /* set up registers for signal handler */ - __frame->sp = (unsigned long) frame; - __frame->lr = (unsigned long) &frame->retcode; - __frame->gr8 = sig; - + /* Set up registers for the signal handler */ if (current->personality & FDPIC_FUNCPTRS) { struct fdpic_func_descriptor __user *funcptr = (struct fdpic_func_descriptor __user *) ka->sa.sa_handler; - __get_user(__frame->pc, &funcptr->text); - __get_user(__frame->gr15, &funcptr->GOT); + struct fdpic_func_descriptor desc; + if (copy_from_user(&desc, funcptr, sizeof(desc))) + goto give_sigsegv; + __frame->pc = desc.text; + __frame->gr15 = desc.GOT; } else { __frame->pc = (unsigned long) ka->sa.sa_handler; __frame->gr15 = 0; } - set_fs(USER_DS); + __frame->sp = (unsigned long) frame; + __frame->lr = (unsigned long) &frame->retcode; + __frame->gr8 = sig; /* the tracer may want to single-step inside the handler */ if (test_thread_flag(TIF_SINGLESTEP)) @@ -341,6 +344,8 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, struct rt_sigframe __user *frame; int rsig; + set_fs(USER_DS); + frame = get_sigframe(ka, sizeof(*frame)); if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) @@ -395,22 +400,23 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, } /* Set up registers for signal handler */ - __frame->sp = (unsigned long) frame; - __frame->lr = (unsigned long) &frame->retcode; - __frame->gr8 = sig; - __frame->gr9 = (unsigned long) &frame->info; - if (current->personality & FDPIC_FUNCPTRS) { struct fdpic_func_descriptor __user *funcptr = (struct fdpic_func_descriptor __user *) ka->sa.sa_handler; - __get_user(__frame->pc, &funcptr->text); - __get_user(__frame->gr15, &funcptr->GOT); + struct fdpic_func_descriptor desc; + if (copy_from_user(&desc, funcptr, sizeof(desc))) + goto give_sigsegv; + __frame->pc = desc.text; + __frame->gr15 = desc.GOT; } else { __frame->pc = (unsigned long) ka->sa.sa_handler; __frame->gr15 = 0; } - set_fs(USER_DS); + __frame->sp = (unsigned long) frame; + __frame->lr = (unsigned long) &frame->retcode; + __frame->gr8 = sig; + __frame->gr9 = (unsigned long) &frame->info; /* the tracer may want to single-step inside the handler */ if (test_thread_flag(TIF_SINGLESTEP)) -- 2.20.1