linux-kernel - [PATCH v3 03/12] binfmt_flat: prevent kernel dammage from corrupted executable headers

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Message-Id: <1468988424-32671-4-git-send-email-nicolas.pitre@linaro.org>
Date:	Wed, 20 Jul 2016 00:20:15 -0400
From:	Nicolas Pitre <nicolas.pitre@...aro.org>
To:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	Alexander Viro <viro@...iv.linux.org.uk>,
	David Howells <dhowells@...hat.com>,
	Greg Ungerer <gerg@...ux-m68k.org>
Subject: [PATCH v3 03/12] binfmt_flat: prevent kernel dammage from corrupted executable headers

Signed-off-by: Nicolas Pitre <nico@...aro.org>
---
 fs/binfmt_flat.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index 36f5bb6b2c..9c76d9a222 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -470,6 +470,17 @@ static int load_flat_file(struct linux_binprm * bprm,
 	}
 
 	/*
+	 * Make sure the header params are sane.
+	 * 28 bits (256 MB) is way more than reasonable in this case.
+	 * If some top bits are set we have probable binary corruption.
+	*/
+	if ((text_len | data_len | bss_len | stack_len | full_data) >> 28) {
+		pr_err("bad header\n");
+		ret = -ENOEXEC;
+		goto err;
+	}
+
+	/*
 	 * fix up the flags for the older format,  there were all kinds
 	 * of endian hacks,  this only works for the simple cases
 	 */
-- 
2.7.4