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[PATCH] VM/Security: add security hook to do_brk

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From: Eric Paris <eparis@...>
To: <linux-kernel@...>
Cc: <jmorris@...>, <alan@...>, <chrisw@...>, <akpm@...>, <linux-security-module@...>, <solar@...>, <wtarreau@...>
Subject: [PATCH] VM/Security: add security hook to do_brk
Date: Tuesday, December 4, 2007 - 12:06 pm

Given a specifically crafted binary do_brk() can be used to get low
pages available in userspace virtually memory and can thus be used to
circumvent the mmap_min_addr low memory protection.  Add security checks
in do_brk().

Signed-off-by: Eric Paris <eparis@redhat.com>

---

 mm/mmap.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mm/mmap.c b/mm/mmap.c
index f4cfc6a..15678aa 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1941,6 +1941,10 @@ unsigned long do_brk(unsigned long addr, unsigned long len)
 	if (is_hugepage_only_range(mm, addr, len))
 		return -EINVAL;
 
+	error = security_file_mmap(0, 0, 0, 0, addr, 1);
+	if (error)
+		return error;
+
 	flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
 
 	error = arch_mmap_check(addr, len, flags);


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Messages in current thread:
[PATCH] VM/Security: add security hook to do_brk, Eric Paris, (Tue Dec 4, 12:06 pm)
Re: [PATCH] VM/Security: add security hook to do_brk, Alan Cox, (Tue Dec 4, 12:43 pm)
Re: [PATCH] VM/Security: add security hook to do_brk, James Morris, (Wed Dec 5, 8:15 am)