[PATCH v4 03/12] binfmt_flat: prevent kernel dammage from corrupted executable headers

From: Nicolas Pitre
Date: Wed Jul 20 2016 - 15:23:44 EST


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

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
*/
--
2.7.4