[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 <xemul@openvz.org>
Signed-off-by: Kirill Korotaev <dev@openvz.org>
Acked-by: David Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
[ Cleaned up to not affect architectures that don't need it ]
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 51 insertions, 40 deletions

diff --git a/arch/ia64/kernel/sys_ia64.c b/arch/ia64/kernel/sys_ia64.c
index 40722d88607a..9ef62a3fbfad 100644
--- a/arch/ia64/kernel/sys_ia64.c
+++ b/arch/ia64/kernel/sys_ia64.c
@@ -163,10 +163,25 @@ sys_pipe (void)
 	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);
@@ -188,17 +203,6 @@ do_mmap2 (unsigned long addr, unsigned long len, int prot, int flags, int fd, un
 		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;
-	}
-
 	down_write(&current->mm->mmap_sem);
 	addr = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
 	up_write(&current->mm->mmap_sem);
diff --git a/arch/sparc/kernel/sys_sparc.c b/arch/sparc/kernel/sys_sparc.c
index a41c8a5c2007..94ff58c9d4a9 100644
--- a/arch/sparc/kernel/sys_sparc.c
+++ b/arch/sparc/kernel/sys_sparc.c
@@ -219,6 +219,21 @@ out:
 	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,
@@ -233,25 +248,13 @@ static unsigned long do_mmap2(unsigned long addr, unsigned long len,
 			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:
diff --git a/arch/sparc64/kernel/sys_sparc.c b/arch/sparc64/kernel/sys_sparc.c
index 054d0abdb7ee..bf5f14ee73de 100644
--- a/arch/sparc64/kernel/sys_sparc.c
+++ b/arch/sparc64/kernel/sys_sparc.c
@@ -548,6 +548,26 @@ asmlinkage long sparc64_personality(unsigned long personality)
 	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,
@@ -563,27 +583,11 @@ asmlinkage unsigned long sys_mmap(unsigned long addr, unsigned long len,
 	}
 	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: