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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 <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Al Viro 2010-09-20 15:13:09 +01:00 committed by Linus Torvalds
parent 20cd514d0f
commit 5f4ad04a1e
1 changed files with 22 additions and 16 deletions
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38
arch/frv/kernel/signal.c
View File

@ -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))