[PATCH] IA64,sparc: local DoS with corrupted ELFs

This prevents cross-region mappings on IA64 and SPARC which could lead
to system crash. They were correctly trapped for normal mmap() calls,
but not for the kernel internal calls generated by executable loading.

This code just moves the architecture-specific cross-region checks into
an arch-specific "arch_mmap_check()" macro, and defines that for the
architectures that needed it (ia64, sparc and sparc64).

Architectures that don't have any special requirements can just ignore
the new cross-region check, since the mmap() code will just notice on
its own when the macro isn't defined.

Signed-off-by: Pavel Emelianov <[e-mail]>
Signed-off-by: Kirill Korotaev <[e-mail]>
Acked-by: David Miller <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>
[ Cleaned up to not affect architectures that don't need it ]
Signed-off-by: Linus Torvalds <[e-mail]>

arch/ia64/kernel/sys_ia64.c

···
 	return retval;
 }
 
+int ia64_mmap_check(unsigned long addr, unsigned long len,
+		unsigned long flags)
+{
+	unsigned long roff;
+
+	/*
+	 * Don't permit mappings into unmapped space, the virtual page table
+	 * of a region, or across a region boundary.  Note: RGN_MAP_LIMIT is
+	 * equal to 2^n-PAGE_SIZE (for some integer n <= 61) and len > 0.
+	 */
+	roff = REGION_OFFSET(addr);
+	if ((len > RGN_MAP_LIMIT) || (roff > (RGN_MAP_LIMIT - len)))
+		return -EINVAL;
+	return 0;
+}
+
 static inline unsigned long
 do_mmap2 (unsigned long addr, unsigned long len, int prot, int flags, int fd, unsigned long pgoff)
 {
-	unsigned long roff;
 	struct file *file = NULL;
 
 	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
···
 	/* Careful about overflows.. */
 	len = PAGE_ALIGN(len);
 	if (!len || len > TASK_SIZE) {
-		addr = -EINVAL;
-		goto out;
-	}
-
-	/*
-	 * Don't permit mappings into unmapped space, the virtual page table of a region,
-	 * or across a region boundary.  Note: RGN_MAP_LIMIT is equal to 2^n-PAGE_SIZE
-	 * (for some integer n <= 61) and len > 0.
-	 */
-	roff = REGION_OFFSET(addr);
-	if ((len > RGN_MAP_LIMIT) || (roff > (RGN_MAP_LIMIT - len))) {
 		addr = -EINVAL;
 		goto out;
 	}

arch/sparc/kernel/sys_sparc.c

···
 	return err;
 }
 
+int sparc_mmap_check(unsigned long addr, unsigned long len, unsigned long flags)
+{
+	if (ARCH_SUN4C_SUN4 &&
+	    (len > 0x20000000 ||
+	     ((flags & MAP_FIXED) &&
+	      addr < 0xe0000000 && addr + len > 0x20000000)))
+		return -EINVAL;
+
+	/* See asm-sparc/uaccess.h */
+	if (len > TASK_SIZE - PAGE_SIZE || addr + len > TASK_SIZE - PAGE_SIZE)
+		return -EINVAL;
+
+	return 0;
+}
+
 /* Linux version of mmap */
 static unsigned long do_mmap2(unsigned long addr, unsigned long len,
 	unsigned long prot, unsigned long flags, unsigned long fd,
···
 			goto out;
 	}
 
-	retval = -EINVAL;
 	len = PAGE_ALIGN(len);
-	if (ARCH_SUN4C_SUN4 &&
-	    (len > 0x20000000 ||
-	     ((flags & MAP_FIXED) &&
-	      addr < 0xe0000000 && addr + len > 0x20000000)))
-		goto out_putf;
-
-	/* See asm-sparc/uaccess.h */
-	if (len > TASK_SIZE - PAGE_SIZE || addr + len > TASK_SIZE - PAGE_SIZE)
-		goto out_putf;
-
 	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
 
 	down_write(&current->mm->mmap_sem);
 	retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
 	up_write(&current->mm->mmap_sem);
 
-out_putf:
 	if (file)
 		fput(file);
 out:

arch/sparc64/kernel/sys_sparc.c

···
 	return ret;
 }
 
+int sparc64_mmap_check(unsigned long addr, unsigned long len,
+		unsigned long flags)
+{
+	if (test_thread_flag(TIF_32BIT)) {
+		if (len >= STACK_TOP32)
+			return -EINVAL;
+
+		if ((flags & MAP_FIXED) && addr > STACK_TOP32 - len)
+			return -EINVAL;
+	} else {
+		if (len >= VA_EXCLUDE_START)
+			return -EINVAL;
+
+		if ((flags & MAP_FIXED) && invalid_64bit_range(addr, len))
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
 /* Linux version of mmap */
 asmlinkage unsigned long sys_mmap(unsigned long addr, unsigned long len,
 	unsigned long prot, unsigned long flags, unsigned long fd,
···
 	}
 	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
 	len = PAGE_ALIGN(len);
-	retval = -EINVAL;
-
-	if (test_thread_flag(TIF_32BIT)) {
-		if (len >= STACK_TOP32)
-			goto out_putf;
-
-		if ((flags & MAP_FIXED) && addr > STACK_TOP32 - len)
-			goto out_putf;
-	} else {
-		if (len >= VA_EXCLUDE_START)
-			goto out_putf;
-
-		if ((flags & MAP_FIXED) && invalid_64bit_range(addr, len))
-			goto out_putf;
-	}
 
 	down_write(&current->mm->mmap_sem);
 	retval = do_mmap(file, addr, len, prot, flags, off);
 	up_write(&current->mm->mmap_sem);
 
-out_putf:
 	if (file)
 		fput(file);
 out:

include/asm-ia64/mman.h

···
 #define MCL_CURRENT	1		/* lock all current mappings */
 #define MCL_FUTURE	2		/* lock all future mappings */
 
+#ifdef __KERNEL__
+#ifndef __ASSEMBLY__
+#define arch_mmap_check	ia64_mmap_check
+int ia64_mmap_check(unsigned long addr, unsigned long len,
+		unsigned long flags);
+#endif
+#endif
+
 #endif /* _ASM_IA64_MMAN_H */

include/asm-sparc/mman.h

···
 
 #define MADV_FREE	0x5		/* (Solaris) contents can be freed */
 
+#ifdef __KERNEL__
+#ifndef __ASSEMBLY__
+#define arch_mmap_check	sparc_mmap_check
+int sparc_mmap_check(unsigned long addr, unsigned long len,
+		unsigned long flags);
+#endif
+#endif
+
 #endif /* __SPARC_MMAN_H__ */

include/asm-sparc64/mman.h

···
 
 #define MADV_FREE	0x5		/* (Solaris) contents can be freed */
 
+#ifdef __KERNEL__
+#ifndef __ASSEMBLY__
+#define arch_mmap_check	sparc64_mmap_check
+int sparc64_mmap_check(unsigned long addr, unsigned long len,
+		unsigned long flags);
+#endif
+#endif
+
 #endif /* __SPARC64_MMAN_H__ */

mm/mmap.c

···
 #include <asm/cacheflush.h>
 #include <asm/tlb.h>
 
+#ifndef arch_mmap_check
+#define arch_mmap_check(addr, len, flags)	(0)
+#endif
+
 static void unmap_region(struct mm_struct *mm,
 		struct vm_area_struct *vma, struct vm_area_struct *prev,
 		unsigned long start, unsigned long end);
···
 
 	if (!len)
 		return -EINVAL;
+
+	error = arch_mmap_check(addr, len, flags);
+	if (error)
+		return error;
 
 	/* Careful about overflows.. */
 	len = PAGE_ALIGN(len);
···
 	unsigned long flags;
 	struct rb_node ** rb_link, * rb_parent;
 	pgoff_t pgoff = addr >> PAGE_SHIFT;
+	int error;
 
 	len = PAGE_ALIGN(len);
 	if (!len)
···
 
 	if ((addr + len) > TASK_SIZE || (addr + len) < addr)
 		return -EINVAL;
+
+	flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
+
+	error = arch_mmap_check(addr, len, flags);
+	if (error)
+		return error;
 
 	/*
 	 * mlock MCL_FUTURE?
···
 
 	if (security_vm_enough_memory(len >> PAGE_SHIFT))
 		return -ENOMEM;
-
-	flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
 
 	/* Can we just expand an old private anonymous mapping? */
 	if (vma_merge(mm, prev, addr, addr + len, flags,