From: Nicolas Pitre <nicolas.pitre@linaro.org>
Date: Sun, 24 Jul 2016 15:30:17 +0000 (-0400)
Subject: binfmt_flat: prevent kernel dammage from corrupted executable headers
X-Git-Tag: v4.8-rc1~42^2~10
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=c995ee28d29d;p=linux-block.git

binfmt_flat: prevent kernel dammage from corrupted executable headers

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>
---

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index c3ccdefdeac2..03301bad1f9b 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -465,6 +465,17 @@ static int load_flat_file(struct linux_binprm *bprm,
 		goto err;
 	}
 
+	/*
+	 * 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