From: Oleg Nesterov <oleg@redhat.com>
Date: Fri, 15 Jun 2012 15:43:25 +0000 (+0200)
Subject: uprobes: __copy_insn() should ensure a_ops->readpage != NULL
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=cc359d180fa9c25a4c1819f17e07a422d788353d;p=openwrt%2Fstaging%2Fblogic.git

uprobes: __copy_insn() should ensure a_ops->readpage != NULL

__copy_insn() blindly calls read_mapping_page(), this will crash
the kernel if ->readpage == NULL, add the necessary check. For
example, hugetlbfs_aops->readpage is NULL. Perhaps we should
change read_mapping_page() instead.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anton Arapov <anton@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20120615154325.GA9568@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index f0d04530af63..604930bf9c92 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -610,6 +610,9 @@ __copy_insn(struct address_space *mapping, struct vm_area_struct *vma, char *ins
 	if (!filp)
 		return -EINVAL;
 
+	if (!mapping->a_ops->readpage)
+		return -EIO;
+
 	idx = (unsigned long)(offset >> PAGE_CACHE_SHIFT);
 	off1 = offset &= ~PAGE_MASK;