Commit 24962af7 authored Jul 13, 2018 by Oscar Salvador Committed by Linus Torvalds Jul 14, 2018

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

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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent fa8cbda8

fs/binfmt_elf.c

+2 −3

Original line number	Diff line number	Diff line
		@@ -1259,9 +1259,8 @@ 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 (error)

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