[PATCH 1/5] frv: restart_block.fn needs to be reset on sigreturn

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* [PATCH 1/5] frv: restart_block.fn needs to be reset on sigreturn
@ 2010-09-20 14:13 David Howells
  2010-09-20 14:13 ` [PATCH 2/5] frv: fix address verification holes in setup_frame/setup_rt_frame David Howells
                   ` (3 more replies)
  0 siblings, 4 replies; 6+ messages in thread
From: David Howells @ 2010-09-20 14:13 UTC (permalink / raw)
  To: torvalds, akpm; +Cc: linux-kernel, Al Viro, David Howells

From: Al Viro <viro@ftp.linux.org.uk>

Reset restart_block.fn on executing a sigreturn such that any currently pending
system call restarts will be forced to return -EINTR.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
---

 arch/frv/kernel/signal.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)


diff --git a/arch/frv/kernel/signal.c b/arch/frv/kernel/signal.c
index 0974c0e..7fc2961 100644
--- a/arch/frv/kernel/signal.c
+++ b/arch/frv/kernel/signal.c
@@ -121,6 +121,9 @@ static int restore_sigcontext(struct sigcontext __user *sc, int *_gr8)
 	struct user_context *user = current->thread.user;
 	unsigned long tbr, psr;
 
+	/* Always make any pending restarted system calls return -EINTR */
+	current_thread_info()->restart_block.fn = do_no_restart_syscall;
+
 	tbr = user->i.tbr;
 	psr = user->i.psr;
 	if (copy_from_user(user, &sc->sc_context, sizeof(sc->sc_context)))


^ permalink raw reply	[flat|nested] 6+ messages in thread

* [PATCH 2/5] frv: fix address verification holes in setup_frame/setup_rt_frame
  2010-09-20 14:13 [PATCH 1/5] frv: restart_block.fn needs to be reset on sigreturn David Howells
@ 2010-09-20 14:13 ` David Howells
  2010-09-20 14:13 ` [PATCH 3/5] frv: avoid infinite loop of SIGSEGV delivery David Howells
                   ` (2 subsequent siblings)
  3 siblings, 0 replies; 6+ messages in thread
From: David Howells @ 2010-09-20 14:13 UTC (permalink / raw)
  To: torvalds, akpm; +Cc: linux-kernel, Al Viro, David Howells

From: Al Viro <viro@ftp.linux.org.uk>

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>
---

 arch/frv/kernel/signal.c |   38 ++++++++++++++++++++++----------------
 1 files changed, 22 insertions(+), 16 deletions(-)


diff --git a/arch/frv/kernel/signal.c b/arch/frv/kernel/signal.c
index 7fc2961..5fb2d06 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))


^ permalink raw reply	[flat|nested] 6+ messages in thread

* [PATCH 3/5] frv: avoid infinite loop of SIGSEGV delivery
  2010-09-20 14:13 [PATCH 1/5] frv: restart_block.fn needs to be reset on sigreturn David Howells
  2010-09-20 14:13 ` [PATCH 2/5] frv: fix address verification holes in setup_frame/setup_rt_frame David Howells
@ 2010-09-20 14:13 ` David Howells
  2010-09-20 14:13 ` [PATCH 4/5] frv: handling of restart into restart_syscall is fscked David Howells
  2010-09-20 14:13 ` [PATCH 5/5] frv: double syscall restarts, syscall restart in sigreturn() David Howells
  3 siblings, 0 replies; 6+ messages in thread
From: David Howells @ 2010-09-20 14:13 UTC (permalink / raw)
  To: torvalds, akpm; +Cc: linux-kernel, Al Viro, David Howells

From: Al Viro <viro@ftp.linux.org.uk>

Use force_sigsegv() rather than force_sig(SIGSEGV, ...) as the former resets
the SEGV handler pointer which will kill the process, rather than leaving it
open to an infinite loop if the SEGV handler itself caused a SEGV signal.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
---

 arch/frv/kernel/signal.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)


diff --git a/arch/frv/kernel/signal.c b/arch/frv/kernel/signal.c
index 5fb2d06..48203c6 100644
--- a/arch/frv/kernel/signal.c
+++ b/arch/frv/kernel/signal.c
@@ -329,7 +329,7 @@ static int setup_frame(int sig, struct k_sigaction *ka, sigset_t *set)
 	return 0;
 
 give_sigsegv:
-	force_sig(SIGSEGV, current);
+	force_sigsegv(sig, current);
 	return -EFAULT;
 
 } /* end setup_frame() */
@@ -431,7 +431,7 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 	return 0;
 
 give_sigsegv:
-	force_sig(SIGSEGV, current);
+	force_sigsegv(sig, current);
 	return -EFAULT;
 
 } /* end setup_rt_frame() */


^ permalink raw reply	[flat|nested] 6+ messages in thread

* [PATCH 4/5] frv: handling of restart into restart_syscall is fscked
  2010-09-20 14:13 [PATCH 1/5] frv: restart_block.fn needs to be reset on sigreturn David Howells
  2010-09-20 14:13 ` [PATCH 2/5] frv: fix address verification holes in setup_frame/setup_rt_frame David Howells
  2010-09-20 14:13 ` [PATCH 3/5] frv: avoid infinite loop of SIGSEGV delivery David Howells
@ 2010-09-20 14:13 ` David Howells
  2010-09-20 14:13 ` [PATCH 5/5] frv: double syscall restarts, syscall restart in sigreturn() David Howells
  3 siblings, 0 replies; 6+ messages in thread
From: David Howells @ 2010-09-20 14:13 UTC (permalink / raw)
  To: torvalds, akpm; +Cc: linux-kernel, Al Viro, David Howells

From: Al Viro <viro@ftp.linux.org.uk>

do_signal() should place the syscall number in gr7, not gr8 when handling
ERESTART_WOULDBLOCK.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
---

 arch/frv/kernel/signal.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)


diff --git a/arch/frv/kernel/signal.c b/arch/frv/kernel/signal.c
index 48203c6..bd13b57 100644
--- a/arch/frv/kernel/signal.c
+++ b/arch/frv/kernel/signal.c
@@ -547,7 +547,7 @@ no_signal:
 			break;
 
 		case -ERESTART_RESTARTBLOCK:
-			__frame->gr8 = __NR_restart_syscall;
+			__frame->gr7 = __NR_restart_syscall;
 			__frame->pc -= 4;
 			break;
 		}


^ permalink raw reply	[flat|nested] 6+ messages in thread

* [PATCH 5/5] frv: double syscall restarts, syscall restart in sigreturn()
  2010-09-20 14:13 [PATCH 1/5] frv: restart_block.fn needs to be reset on sigreturn David Howells
                   ` (2 preceding siblings ...)
  2010-09-20 14:13 ` [PATCH 4/5] frv: handling of restart into restart_syscall is fscked David Howells
@ 2010-09-20 14:13 ` David Howells
  3 siblings, 0 replies; 6+ messages in thread
From: David Howells @ 2010-09-20 14:13 UTC (permalink / raw)
  To: torvalds, akpm; +Cc: linux-kernel, Al Viro, David Howells

From: Al Viro <viro@ftp.linux.org.uk>

We need to make sure that only the first do_signal() to be handled
on the way out syscall will bother with syscall restarts; additionally,
the check on the "signal has user handler" path had been wrong -
compare with restart prevention in sigreturn()...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
---

 arch/frv/kernel/signal.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)


diff --git a/arch/frv/kernel/signal.c b/arch/frv/kernel/signal.c
index bd13b57..bab0129 100644
--- a/arch/frv/kernel/signal.c
+++ b/arch/frv/kernel/signal.c
@@ -446,7 +446,7 @@ static int handle_signal(unsigned long sig, siginfo_t *info,
 	int ret;
 
 	/* Are we from a system call? */
-	if (in_syscall(__frame)) {
+	if (__frame->syscallno != -1) {
 		/* If so, check system call restarting.. */
 		switch (__frame->gr8) {
 		case -ERESTART_RESTARTBLOCK:
@@ -465,6 +465,7 @@ static int handle_signal(unsigned long sig, siginfo_t *info,
 			__frame->gr8 = __frame->orig_gr8;
 			__frame->pc -= 4;
 		}
+		__frame->syscallno = -1;
 	}
 
 	/* Set up the stack frame */
@@ -551,6 +552,7 @@ no_signal:
 			__frame->pc -= 4;
 			break;
 		}
+		__frame->syscallno = -1;
 	}
 
 	/* if there's no signal to deliver, we just put the saved sigmask


^ permalink raw reply	[flat|nested] 6+ messages in thread

* [PATCH 3/5] frv: avoid infinite loop of SIGSEGV delivery
@ 2010-09-18 19:41 Al Viro
  0 siblings, 0 replies; 6+ messages in thread
From: Al Viro @ 2010-09-18 19:41 UTC (permalink / raw)
  To: linux-arch; +Cc: dhowells, linux-kernel


force_sigsegv() exists for a good reason...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 arch/frv/kernel/signal.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/frv/kernel/signal.c b/arch/frv/kernel/signal.c
index d06226b..fa40d54 100644
--- a/arch/frv/kernel/signal.c
+++ b/arch/frv/kernel/signal.c
@@ -329,7 +329,7 @@ static int setup_frame(int sig, struct k_sigaction *ka, sigset_t *set)
 	return 0;
 
 give_sigsegv:
-	force_sig(SIGSEGV, current);
+	force_sigsegv(sig, current);
 	return -EFAULT;
 
 } /* end setup_frame() */
@@ -431,7 +431,7 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 	return 0;
 
 give_sigsegv:
-	force_sig(SIGSEGV, current);
+	force_sigsegv(sig, current);
 	return -EFAULT;
 
 } /* end setup_rt_frame() */
-- 
1.5.6.5



^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2010-09-20 14:13 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2010-09-20 14:13 [PATCH 1/5] frv: restart_block.fn needs to be reset on sigreturn David Howells
2010-09-20 14:13 ` [PATCH 2/5] frv: fix address verification holes in setup_frame/setup_rt_frame David Howells
2010-09-20 14:13 ` [PATCH 3/5] frv: avoid infinite loop of SIGSEGV delivery David Howells
2010-09-20 14:13 ` [PATCH 4/5] frv: handling of restart into restart_syscall is fscked David Howells
2010-09-20 14:13 ` [PATCH 5/5] frv: double syscall restarts, syscall restart in sigreturn() David Howells
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