Linux-libre 4.5-gnu

19 files changed, 275 insertions, 88 deletions

diff --git a/arch/um/Kconfig.common b/arch/um/Kconfig.common
index d195a87ca..cc0013475 100644
--- a/arch/um/Kconfig.common
+++ b/arch/um/Kconfig.common
@@ -2,6 +2,7 @@ config UML
 	bool
 	default y
 	select HAVE_ARCH_AUDITSYSCALL
+	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_UID16
 	select HAVE_FUTEX_CMPXCHG if FUTEX
 	select GENERIC_IRQ_SHOW
diff --git a/arch/um/Kconfig.um b/arch/um/Kconfig.um
index 28a9885e3..4b2ed5858 100644
--- a/arch/um/Kconfig.um
+++ b/arch/um/Kconfig.um
@@ -104,3 +104,19 @@ config PGTABLE_LEVELS
 	int
 	default 3 if 3_LEVEL_PGTABLES
 	default 2
+
+config SECCOMP
+	def_bool y
+	prompt "Enable seccomp to safely compute untrusted bytecode"
+	---help---
+	  This kernel feature is useful for number crunching applications
+	  that may need to compute untrusted bytecode during their
+	  execution. By using pipes or other transports made available to
+	  the process as file descriptors supporting the read/write
+	  syscalls, it's possible to isolate those applications in
+	  their own address space using seccomp. Once seccomp is
+	  enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
+	  and the task is only allowed to execute a few safe syscalls
+	  defined by each seccomp mode.
+
+	  If unsure, say Y.
diff --git a/arch/um/drivers/hostaudio_kern.c b/arch/um/drivers/hostaudio_kern.c
index f6b911cc3..3a4b58730 100644
--- a/arch/um/drivers/hostaudio_kern.c
+++ b/arch/um/drivers/hostaudio_kern.c
@@ -105,13 +105,9 @@ static ssize_t hostaudio_write(struct file *file, const char __user *buffer,
 	printk(KERN_DEBUG "hostaudio: write called, count = %d\n", count);
 #endif
 
-	kbuf = kmalloc(count, GFP_KERNEL);
-	if (kbuf == NULL)
-		return -ENOMEM;
-
-	err = -EFAULT;
-	if (copy_from_user(kbuf, buffer, count))
-		goto out;
+	kbuf = memdup_user(buffer, count);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
 
 	err = os_write_file(state->fd, kbuf, count);
 	if (err < 0)
diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
index 29880c9b3..b821b13d3 100644
--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -748,19 +748,11 @@ static ssize_t mconsole_proc_write(struct file *file,
 {
 	char *buf;
 
-	buf = kmalloc(count + 1, GFP_KERNEL);
-	if (buf == NULL)
-		return -ENOMEM;
-
-	if (copy_from_user(buf, buffer, count)) {
-		count = -EFAULT;
-		goto out;
-	}
-
-	buf[count] = '\0';
+	buf = memdup_user_nul(buffer, count);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
 
 	mconsole_notify(notify_socket, MCONSOLE_USER_NOTIFY, buf, count);
- out:
 	kfree(buf);
 	return count;
 }
diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index e8ab93c3e..39ba20755 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -535,11 +535,7 @@ static int read_cow_bitmap(int fd, void *buf, int offset, int len)
 {
 	int err;
 
-	err = os_seek_file(fd, offset);
-	if (err < 0)
-		return err;
-
-	err = os_read_file(fd, buf, len);
+	err = os_pread_file(fd, buf, len, offset);
 	if (err < 0)
 		return err;
 
@@ -1377,14 +1373,8 @@ static int update_bitmap(struct io_thread_req *req)
 	if(req->cow_offset == -1)
 		return 0;
 
-	n = os_seek_file(req->fds[1], req->cow_offset);
-	if(n < 0){
-		printk("do_io - bitmap lseek failed : err = %d\n", -n);
-		return 1;
-	}
-
-	n = os_write_file(req->fds[1], &req->bitmap_words,
-			  sizeof(req->bitmap_words));
+	n = os_pwrite_file(req->fds[1], &req->bitmap_words,
+			  sizeof(req->bitmap_words), req->cow_offset);
 	if(n != sizeof(req->bitmap_words)){
 		printk("do_io - bitmap update failed, err = %d fd = %d\n", -n,
 		       req->fds[1]);
@@ -1399,7 +1389,6 @@ static void do_io(struct io_thread_req *req)
 	char *buf;
 	unsigned long len;
 	int n, nsectors, start, end, bit;
-	int err;
 	__u64 off;
 
 	if (req->op == UBD_FLUSH) {
@@ -1428,18 +1417,12 @@ static void do_io(struct io_thread_req *req)
 		len = (end - start) * req->sectorsize;
 		buf = &req->buffer[start * req->sectorsize];
 
-		err = os_seek_file(req->fds[bit], off);
-		if(err < 0){
-			printk("do_io - lseek failed : err = %d\n", -err);
-			req->error = 1;
-			return;
-		}
 		if(req->op == UBD_READ){
 			n = 0;
 			do {
 				buf = &buf[n];
 				len -= n;
-				n = os_read_file(req->fds[bit], buf, len);
+				n = os_pread_file(req->fds[bit], buf, len, off);
 				if (n < 0) {
 					printk("do_io - read failed, err = %d "
 					       "fd = %d\n", -n, req->fds[bit]);
@@ -1449,7 +1432,7 @@ static void do_io(struct io_thread_req *req)
 			} while((n < len) && (n != 0));
 			if (n < len) memset(&buf[n], 0, len - n);
 		} else {
-			n = os_write_file(req->fds[bit], buf, len);
+			n = os_pwrite_file(req->fds[bit], buf, len, off);
 			if(n != len){
 				printk("do_io - write failed err = %d "
 				       "fd = %d\n", -n, req->fds[bit]);
diff --git a/arch/um/include/asm/hardirq.h b/arch/um/include/asm/hardirq.h
new file mode 100644
index 000000000..756f0778e
--- /dev/null
+++ b/arch/um/include/asm/hardirq.h
@@ -0,0 +1,23 @@
+#ifndef __ASM_UM_HARDIRQ_H
+#define __ASM_UM_HARDIRQ_H
+
+#include <linux/cache.h>
+#include <linux/threads.h>
+
+typedef struct {
+	unsigned int __softirq_pending;
+} ____cacheline_aligned irq_cpustat_t;
+
+#include <linux/irq_cpustat.h>	/* Standard mappings for irq_cpustat_t above */
+#include <linux/irq.h>
+
+#ifndef ack_bad_irq
+static inline void ack_bad_irq(unsigned int irq)
+{
+	printk(KERN_CRIT "unexpected IRQ trap at vector %02x\n", irq);
+}
+#endif
+
+#define __ARCH_IRQ_EXIT_IRQS_DISABLED 1
+
+#endif /* __ASM_UM_HARDIRQ_H */
diff --git a/arch/um/include/asm/page.h b/arch/um/include/asm/page.h
index 71c5d1320..f878bec23 100644
--- a/arch/um/include/asm/page.h
+++ b/arch/um/include/asm/page.h
@@ -18,6 +18,7 @@
 
 struct page;
 
+#include <linux/pfn.h>
 #include <linux/types.h>
 #include <asm/vm-flags.h>
 
@@ -33,26 +34,22 @@ struct page;
 
 #if defined(CONFIG_3_LEVEL_PGTABLES) && !defined(CONFIG_64BIT)
 
-typedef struct { unsigned long pte_low, pte_high; } pte_t;
+typedef struct { unsigned long pte; } pte_t;
 typedef struct { unsigned long pmd; } pmd_t;
 typedef struct { unsigned long pgd; } pgd_t;
-#define pte_val(x) ((x).pte_low | ((unsigned long long) (x).pte_high << 32))
-
-#define pte_get_bits(pte, bits) ((pte).pte_low & (bits))
-#define pte_set_bits(pte, bits) ((pte).pte_low |= (bits))
-#define pte_clear_bits(pte, bits) ((pte).pte_low &= ~(bits))
-#define pte_copy(to, from) ({ (to).pte_high = (from).pte_high; \
-			      smp_wmb(); \
-			      (to).pte_low = (from).pte_low; })
-#define pte_is_zero(pte) (!((pte).pte_low & ~_PAGE_NEWPAGE) && !(pte).pte_high)
-#define pte_set_val(pte, phys, prot) \
-	({ (pte).pte_high = (phys) >> 32; \
-	   (pte).pte_low = (phys) | pgprot_val(prot); })
+#define pte_val(p) ((p).pte)
+
+#define pte_get_bits(p, bits) ((p).pte & (bits))
+#define pte_set_bits(p, bits) ((p).pte |= (bits))
+#define pte_clear_bits(p, bits) ((p).pte &= ~(bits))
+#define pte_copy(to, from) ({ (to).pte = (from).pte; })
+#define pte_is_zero(p) (!((p).pte & ~_PAGE_NEWPAGE))
+#define pte_set_val(p, phys, prot) \
+	({ (p).pte = (phys) | pgprot_val(prot); })
 
 #define pmd_val(x)	((x).pmd)
 #define __pmd(x) ((pmd_t) { (x) } )
 
-typedef unsigned long long pfn_t;
 typedef unsigned long long phys_t;
 
 #else
@@ -76,7 +73,6 @@ typedef struct { unsigned long pmd; } pmd_t;
 #define pte_is_zero(p) (!((p).pte & ~_PAGE_NEWPAGE))
 #define pte_set_val(p, phys, prot) (p).pte = (phys | pgprot_val(prot))
 
-typedef unsigned long pfn_t;
 typedef unsigned long phys_t;
 
 #endif
@@ -109,8 +105,8 @@ extern unsigned long uml_physmem;
 #define __pa(virt) to_phys((void *) (unsigned long) (virt))
 #define __va(phys) to_virt((unsigned long) (phys))
 
-#define phys_to_pfn(p) ((pfn_t) ((p) >> PAGE_SHIFT))
-#define pfn_to_phys(pfn) ((phys_t) ((pfn) << PAGE_SHIFT))
+#define phys_to_pfn(p) ((p) >> PAGE_SHIFT)
+#define pfn_to_phys(pfn) PFN_PHYS(pfn)
 
 #define pfn_valid(pfn) ((pfn) < max_mapnr)
 #define virt_addr_valid(v) pfn_valid(phys_to_pfn(__pa(v)))
diff --git a/arch/um/include/asm/pgtable-3level.h b/arch/um/include/asm/pgtable-3level.h
index 2b4274e7c..bae8523a1 100644
--- a/arch/um/include/asm/pgtable-3level.h
+++ b/arch/um/include/asm/pgtable-3level.h
@@ -98,7 +98,7 @@ static inline unsigned long pte_pfn(pte_t pte)
 	return phys_to_pfn(pte_val(pte));
 }
 
-static inline pte_t pfn_pte(pfn_t page_nr, pgprot_t pgprot)
+static inline pte_t pfn_pte(unsigned long page_nr, pgprot_t pgprot)
 {
 	pte_t pte;
 	phys_t phys = pfn_to_phys(page_nr);
@@ -107,7 +107,7 @@ static inline pte_t pfn_pte(pfn_t page_nr, pgprot_t pgprot)
 	return pte;
 }
 
-static inline pmd_t pfn_pmd(pfn_t page_nr, pgprot_t pgprot)
+static inline pmd_t pfn_pmd(unsigned long page_nr, pgprot_t pgprot)
 {
 	return __pmd((page_nr << PAGE_SHIFT) | pgprot_val(pgprot));
 }
diff --git a/arch/um/include/asm/pgtable.h b/arch/um/include/asm/pgtable.h
index 18eb9924d..7485398d0 100644
--- a/arch/um/include/asm/pgtable.h
+++ b/arch/um/include/asm/pgtable.h
@@ -271,7 +271,7 @@ static inline int pte_same(pte_t pte_a, pte_t pte_b)
 
 #define phys_to_page(phys) pfn_to_page(phys_to_pfn(phys))
 #define __virt_to_page(virt) phys_to_page(__pa(virt))
-#define page_to_phys(page) pfn_to_phys((pfn_t) page_to_pfn(page))
+#define page_to_phys(page) pfn_to_phys(page_to_pfn(page))
 #define virt_to_page(addr) __virt_to_page((const unsigned long) addr)
 
 #define mk_pte(page, pgprot) \
diff --git a/arch/um/include/asm/syscall-generic.h b/arch/um/include/asm/syscall-generic.h
new file mode 100644
index 000000000..9fb9cf8cd
--- /dev/null
+++ b/arch/um/include/asm/syscall-generic.h
@@ -0,0 +1,138 @@
+/*
+ * Access to user system call parameters and results
+ *
+ * See asm-generic/syscall.h for function descriptions.
+ *
+ * Copyright (C) 2015 Mickaël Salaün <mic@digikod.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __UM_SYSCALL_GENERIC_H
+#define __UM_SYSCALL_GENERIC_H
+
+#include <asm/ptrace.h>
+#include <linux/err.h>
+#include <linux/sched.h>
+#include <sysdep/ptrace.h>
+
+static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
+{
+
+	return PT_REGS_SYSCALL_NR(regs);
+}
+
+static inline void syscall_rollback(struct task_struct *task,
+				    struct pt_regs *regs)
+{
+	/* do nothing */
+}
+
+static inline long syscall_get_error(struct task_struct *task,
+				     struct pt_regs *regs)
+{
+	const long error = regs_return_value(regs);
+
+	return IS_ERR_VALUE(error) ? error : 0;
+}
+
+static inline long syscall_get_return_value(struct task_struct *task,
+					    struct pt_regs *regs)
+{
+	return regs_return_value(regs);
+}
+
+static inline void syscall_set_return_value(struct task_struct *task,
+					    struct pt_regs *regs,
+					    int error, long val)
+{
+	PT_REGS_SET_SYSCALL_RETURN(regs, (long) error ?: val);
+}
+
+static inline void syscall_get_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned int i, unsigned int n,
+					 unsigned long *args)
+{
+	const struct uml_pt_regs *r = &regs->regs;
+
+	switch (i) {
+	case 0:
+		if (!n--)
+			break;
+		*args++ = UPT_SYSCALL_ARG1(r);
+	case 1:
+		if (!n--)
+			break;
+		*args++ = UPT_SYSCALL_ARG2(r);
+	case 2:
+		if (!n--)
+			break;
+		*args++ = UPT_SYSCALL_ARG3(r);
+	case 3:
+		if (!n--)
+			break;
+		*args++ = UPT_SYSCALL_ARG4(r);
+	case 4:
+		if (!n--)
+			break;
+		*args++ = UPT_SYSCALL_ARG5(r);
+	case 5:
+		if (!n--)
+			break;
+		*args++ = UPT_SYSCALL_ARG6(r);
+	case 6:
+		if (!n--)
+			break;
+	default:
+		BUG();
+		break;
+	}
+}
+
+static inline void syscall_set_arguments(struct task_struct *task,
+					 struct pt_regs *regs,
+					 unsigned int i, unsigned int n,
+					 const unsigned long *args)
+{
+	struct uml_pt_regs *r = &regs->regs;
+
+	switch (i) {
+	case 0:
+		if (!n--)
+			break;
+		UPT_SYSCALL_ARG1(r) = *args++;
+	case 1:
+		if (!n--)
+			break;
+		UPT_SYSCALL_ARG2(r) = *args++;
+	case 2:
+		if (!n--)
+			break;
+		UPT_SYSCALL_ARG3(r) = *args++;
+	case 3:
+		if (!n--)
+			break;
+		UPT_SYSCALL_ARG4(r) = *args++;
+	case 4:
+		if (!n--)
+			break;
+		UPT_SYSCALL_ARG5(r) = *args++;
+	case 5:
+		if (!n--)
+			break;
+		UPT_SYSCALL_ARG6(r) = *args++;
+	case 6:
+		if (!n--)
+			break;
+	default:
+		BUG();
+		break;
+	}
+}
+
+/* See arch/x86/um/asm/syscall.h for syscall_get_arch() definition. */
+
+#endif	/* __UM_SYSCALL_GENERIC_H */
diff --git a/arch/um/include/asm/thread_info.h b/arch/um/include/asm/thread_info.h
index 53968aaf7..053baff03 100644
--- a/arch/um/include/asm/thread_info.h
+++ b/arch/um/include/asm/thread_info.h
@@ -62,11 +62,13 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_SYSCALL_AUDIT	6
 #define TIF_RESTORE_SIGMASK	7
 #define TIF_NOTIFY_RESUME	8
+#define TIF_SECCOMP		9	/* secure computing */
 
 #define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
 #define _TIF_MEMDIE		(1 << TIF_MEMDIE)
 #define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
+#define _TIF_SECCOMP		(1 << TIF_SECCOMP)
 
 #endif
diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index 868e6c3f8..de5d57222 100644
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -146,6 +146,8 @@ extern int os_read_file(int fd, void *buf, int len);
 extern int os_write_file(int fd, const void *buf, int count);
 extern int os_sync_file(int fd);
 extern int os_file_size(const char *file, unsigned long long *size_out);
+extern int os_pread_file(int fd, void *buf, int len, unsigned long long offset);
+extern int os_pwrite_file(int fd, const void *buf, int count, unsigned long long offset);
 extern int os_file_modtime(const char *file, unsigned long *modtime);
 extern int os_pipe(int *fd, int stream, int close_on_exec);
 extern int os_set_fd_async(int fd);
@@ -282,7 +284,6 @@ extern void initial_thread_cb_skas(void (*proc)(void *),
 				 void *arg);
 extern void halt_skas(void);
 extern void reboot_skas(void);
-extern int get_syscall(struct uml_pt_regs *regs);
 
 /* irq.c */
 extern int os_waiting_for_events(struct irq_fd *active_fds);
diff --git a/arch/um/kernel/reboot.c b/arch/um/kernel/reboot.c
index 9bdf67a09..b60a9f8cd 100644
--- a/arch/um/kernel/reboot.c
+++ b/arch/um/kernel/reboot.c
@@ -12,6 +12,7 @@
 #include <skas.h>
 
 void (*pm_power_off)(void);
+EXPORT_SYMBOL(pm_power_off);
 
 static void kill_off_processes(void)
 {
diff --git a/arch/um/kernel/signal.c b/arch/um/kernel/signal.c
index fc8be0e3a..57acbd67d 100644
--- a/arch/um/kernel/signal.c
+++ b/arch/um/kernel/signal.c
@@ -69,7 +69,7 @@ void do_signal(struct pt_regs *regs)
 	struct ksignal ksig;
 	int handled_sig = 0;
 
-	if (get_signal(&ksig)) {
+	while (get_signal(&ksig)) {
 		handled_sig = 1;
 		/* Whee!  Actually deliver the signal.  */
 		handle_signal(&ksig, regs);
diff --git a/arch/um/kernel/skas/syscall.c b/arch/um/kernel/skas/syscall.c
index 1683b8efd..48b0dcbd8 100644
--- a/arch/um/kernel/skas/syscall.c
+++ b/arch/um/kernel/skas/syscall.c
@@ -5,31 +5,38 @@
 
 #include <linux/kernel.h>
 #include <linux/ptrace.h>
+#include <linux/seccomp.h>
 #include <kern_util.h>
 #include <sysdep/ptrace.h>
+#include <sysdep/ptrace_user.h>
 #include <sysdep/syscalls.h>
-#include <os.h>
 
 void handle_syscall(struct uml_pt_regs *r)
 {
 	struct pt_regs *regs = container_of(r, struct pt_regs, regs);
-	long result;
 	int syscall;
 
-	if (syscall_trace_enter(regs)) {
-		result = -ENOSYS;
+	/* Initialize the syscall number and default return value. */
+	UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
+	PT_REGS_SET_SYSCALL_RETURN(regs, -ENOSYS);
+
+	/* Do the secure computing check first; failures should be fast. */
+	if (secure_computing() == -1)
+		return;
+
+	if (syscall_trace_enter(regs))
 		goto out;
-	}
 
-	syscall = get_syscall(r);
+	/* Update the syscall number after orig_ax has potentially been updated
+	 * with ptrace.
+	 */
+	UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
+	syscall = UPT_SYSCALL_NR(r);
 
-	if ((syscall > __NR_syscall_max) || syscall < 0)
-		result = -ENOSYS;
-	else
-		result = EXECUTE_SYSCALL(syscall, regs);
+	if (syscall >= 0 && syscall <= __NR_syscall_max)
+		PT_REGS_SET_SYSCALL_RETURN(regs,
+				EXECUTE_SYSCALL(syscall, regs));
 
 out:
-	PT_REGS_SET_SYSCALL_RETURN(regs, result);
-
 	syscall_trace_leave(regs);
 }
diff --git a/arch/um/os-Linux/file.c b/arch/um/os-Linux/file.c
index 26e016489..2db18cbbb 100644
--- a/arch/um/os-Linux/file.c
+++ b/arch/um/os-Linux/file.c
@@ -264,6 +264,15 @@ int os_read_file(int fd, void *buf, int len)
 	return n;
 }
 
+int os_pread_file(int fd, void *buf, int len, unsigned long long offset)
+{
+	int n = pread(fd, buf, len, offset);
+
+	if (n < 0)
+		return -errno;
+	return n;
+}
+
 int os_write_file(int fd, const void *buf, int len)
 {
 	int n = write(fd, (void *) buf, len);
@@ -282,6 +291,16 @@ int os_sync_file(int fd)
 	return n;
 }
 
+int os_pwrite_file(int fd, const void *buf, int len, unsigned long long offset)
+{
+	int n = pwrite(fd, (void *) buf, len, offset);
+
+	if (n < 0)
+		return -errno;
+	return n;
+}
+
+
 int os_file_size(const char *file, unsigned long long *size_out)
 {
 	struct uml_stat buf;
diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
index 897e9ad0c..8b1767668 100644
--- a/arch/um/os-Linux/mem.c
+++ b/arch/um/os-Linux/mem.c
@@ -106,6 +106,17 @@ static int __init make_tempfile(const char *template)
 		}
 	}
 
+#ifdef O_TMPFILE
+	fd = open(tempdir, O_CLOEXEC | O_RDWR | O_EXCL | O_TMPFILE, 0700);
+	/*
+	 * If the running system does not support O_TMPFILE flag then retry
+	 * without it.
+	 */
+	if (fd != -1 || (errno != EINVAL && errno != EISDIR &&
+			errno != EOPNOTSUPP))
+		return fd;
+#endif
+
 	tempname = malloc(strlen(tempdir) + strlen(template) + 1);
 	if (tempname == NULL)
 		return -1;
@@ -142,12 +153,6 @@ static int __init create_tmp_file(unsigned long long len)
 	if (fd < 0)
 		exit(1);
 
-	err = fchmod(fd, 0777);
-	if (err < 0) {
-		perror("fchmod");
-		exit(1);
-	}
-
 	/*
 	 * Seek to len - 1 because writing a character there will
 	 * increase the file size by one byte, to the desired length.
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index c211153ca..780166651 100644
--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -62,6 +62,7 @@ static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)
 
 static int signals_enabled;
 static unsigned int signals_pending;
+static unsigned int signals_active = 0;
 
 void sig_handler(int sig, struct siginfo *si, mcontext_t *mc)
 {
@@ -101,7 +102,12 @@ void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
 
 	block_signals();
 
+	signals_active |= SIGALRM_MASK;
+
 	timer_real_alarm_handler(mc);
+
+	signals_active &= ~SIGALRM_MASK;
+
 	set_signals(enabled);
 }
 
@@ -286,8 +292,16 @@ void unblock_signals(void)
 		if (save_pending & SIGIO_MASK)
 			sig_handler_common(SIGIO, NULL, NULL);
 
-		if (save_pending & SIGALRM_MASK)
+		/* Do not reenter the handler */
+
+		if ((save_pending & SIGALRM_MASK) && (!(signals_active & SIGALRM_MASK)))
 			timer_real_alarm_handler(NULL);
+
+		/* Rerun the loop only if there is still pending SIGIO and not in TIMER handler */
+
+		if (!(signals_pending & SIGIO_MASK) && (signals_active & SIGALRM_MASK))
+			return;
+
 	}
 }
 
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index b856c66eb..23025d645 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -172,13 +172,6 @@ static void handle_trap(int pid, struct uml_pt_regs *regs,
 	handle_syscall(regs);
 }
 
-int get_syscall(struct uml_pt_regs *regs)
-{
-	UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->gp);
-
-	return UPT_SYSCALL_NR(regs);
-}
-
 extern char __syscall_stub_start[];
 
 static int userspace_tramp(void *stack)