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[v5,03/15] binfmt_flat: prevent kernel dammage from corrupted executable headers

Message ID 1469374229-21585-4-git-send-email-nicolas.pitre@linaro.org
State Accepted
Commit c995ee28d29d6f256c3a8a6c4e66469554374f25
Headers show

Commit Message

Nicolas Pitre July 24, 2016, 3:30 p.m. UTC 
Signed-off-by: Nicolas Pitre <nico@linaro.org>

---
 fs/binfmt_flat.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

-- 
2.7.4
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Patch

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index c3ccdefdea..03301bad1f 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -466,6 +466,17 @@  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
 	 */