This is a note to let you know that I've just added the patch titled
binfmt_elf: Do not move brk for INTERP-less ET_EXEC
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
binfmt_elf-do-not-move-brk-for-interp-less-et_exec.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7be3cb019db1cbd5fd5ffe6d64a23fefa4b6f229 Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@xxxxxxxxxxxx>
Date: Thu, 26 Sep 2019 10:15:25 -0700
Subject: binfmt_elf: Do not move brk for INTERP-less ET_EXEC
From: Kees Cook <keescook@xxxxxxxxxxxx>
commit 7be3cb019db1cbd5fd5ffe6d64a23fefa4b6f229 upstream.
When brk was moved for binaries without an interpreter, it should have
been limited to ET_DYN only. In other words, the special case was an
ET_DYN that lacks an INTERP, not just an executable that lacks INTERP.
The bug manifested for giant static executables, where the brk would end
up in the middle of the text area on 32-bit architectures.
Reported-and-tested-by: Richard Kojedzinszky <richard@xxxxxxxxx>
Fixes: bbdc6076d2e5 ("binfmt_elf: move brk out of mmap when doing direct loader exec")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/binfmt_elf.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1104,7 +1104,8 @@ static int load_elf_binary(struct linux_
* (since it grows up, and may collide early with the stack
* growing down), and into the unused ELF_ET_DYN_BASE region.
*/
- if (IS_ENABLED(CONFIG_ARCH_HAS_ELF_RANDOMIZE) && !interpreter)
+ if (IS_ENABLED(CONFIG_ARCH_HAS_ELF_RANDOMIZE) &&
+ loc->elf_ex.e_type == ET_DYN && !interpreter)
current->mm->brk = current->mm->start_brk =
ELF_ET_DYN_BASE;
Patches currently in stable-queue which might be from keescook@xxxxxxxxxxxx are
queue-4.4/binfmt_elf-move-brk-out-of-mmap-when-doing-direct-loader-exec.patch
queue-4.4/binfmt_elf-do-not-move-brk-for-interp-less-et_exec.patch
