The current code return the address instead of using PTR_ERR.

Also the check is done after adding e_entry. This can cause weird behaviour
because -errno + loc->interp_elf_ex.e_entry can produce a valid address.

Add a check to test load error before adding entry address. Also in this
case send SIGKILL instead of SIGSEGV to match what is done when loading binary.

Signed-off-by: Matthieu CASTET <matthieu.cas...@parrot.com>
Cc: Al Viro <v...@zeniv.linux.org.uk>
Cc: Andrew Morton <a...@linux-foundation.org>
---
 fs/binfmt_elf.c |   21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 3939829..8397f80 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -900,18 +900,21 @@ static int load_elf_binary(struct linux_binprm *bprm)
                                            interpreter,
                                            &interp_map_addr,
                                            load_bias);
-               if (!IS_ERR((void *)elf_entry)) {
-                       /*
-                        * load_elf_interp() returns relocation
-                        * adjustment
-                        */
-                       interp_load_addr = elf_entry;
-                       elf_entry += loc->interp_elf_ex.e_entry;
+               if (BAD_ADDR(elf_entry)) {
+                       force_sig(SIGKILL, current);
+                       retval = IS_ERR((void *)elf_entry) ?
+                                       PTR_ERR((void *)elf_entry) : -EINVAL;
+                       goto out_free_dentry;
                }
+               /*
+                * load_elf_interp() returns relocation
+                * adjustment
+                */
+               interp_load_addr = elf_entry;
+               elf_entry += loc->interp_elf_ex.e_entry;
                if (BAD_ADDR(elf_entry)) {
                        force_sig(SIGSEGV, current);
-                       retval = IS_ERR((void *)elf_entry) ?
-                                       (int)elf_entry : -EINVAL;
+                       retval = -EINVAL;
                        goto out_free_dentry;
                }
                reloc_func_desc = interp_load_addr;
-- 
1.7.10.4

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