From: Oscar Salvador <osalvador@suse.de>
Date: Fri, 13 Jul 2018 23:59:13 +0000 (-0700)
Subject: fs, elf: make sure to page align bss in load_elf_library
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=a0b71d1b894556ae8e346596046e4f8bb0689f43;p=sagit-ice-cold%2Fkernel_xiaomi_msm8998.git

fs, elf: make sure to page align bss in load_elf_library

commit 24962af7e1041b7e50c1bc71d8d10dc678c556b5 upstream.

The current code does not make sure to page align bss before calling
vm_brk(), and this can lead to a VM_BUG_ON() in __mm_populate() due to
the requested lenght not being correctly aligned.

Let us make sure to align it properly.

Kees: only applicable to CONFIG_USELIB kernels: 32-bit and configured
for libc5.

Link: http://lkml.kernel.org/r/20180705145539.9627-1-osalvador@techadventures.net
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Reported-by: syzbot+5dcb560fe12aa5091c06@syzkaller.appspotmail.com
Tested-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 2963a23f7a80..f010d6c8dd14 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1214,9 +1214,8 @@ static int load_elf_library(struct file *file)
 		goto out_free_ph;
 	}
 
-	len = ELF_PAGESTART(eppnt->p_filesz + eppnt->p_vaddr +
-			    ELF_MIN_ALIGN - 1);
-	bss = eppnt->p_memsz + eppnt->p_vaddr;
+	len = ELF_PAGEALIGN(eppnt->p_filesz + eppnt->p_vaddr);
+	bss = ELF_PAGEALIGN(eppnt->p_memsz + eppnt->p_vaddr);
 	if (bss > len) {
 		error = vm_brk(len, bss - len);
 		if (BAD_ADDR(error))