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>

1 files changed, 11 insertions, 0 deletions

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
@@ -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
          */