ia64/sparc: fix local DoS with corrupted ELFs (CVE-2006-4538)

This patch prevents cross-region mappings
on IA64 and SPARC which could lead to system crash.

Adrian Bunk:
Adapted to 2.6.16.

Signed-Off-By: Kirill Korotaev <dev@openvz.org>
Signed-off-by: Adrian Bunk <bunk@stusta.de>

1 files changed, 15 insertions, 12 deletions

diff --git a/arch/sparc/kernel/sys_sparc.c b/arch/sparc/kernel/sys_sparc.c
index 0cdfc9d294b4..fc8cdcc206b8 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: