[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>

1 files changed, 16 insertions, 12 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);