linux-kernel - [PATCH 07/10] FDPIC: Don't attempt to expand the userspace stack to fill the space allocated [ver #3]

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20090108125422.28454.99617.stgit@warthog.procyon.org.uk>
Date:	Thu, 08 Jan 2009 12:54:22 +0000
From:	David Howells <dhowells@...hat.com>
To:	torvalds@...l.org, akpm@...ux-foundation.org
Cc:	bernds_cb1@...nline.de, dhowells@...hat.com,
	rgetz@...ckfin.uclinux.org, vapier.adi@...il.com,
	lethal@...ux-sh.org, linux-kernel@...r.kernel.org
Subject: [PATCH 07/10] FDPIC: Don't attempt to expand the userspace stack to
	fill the space allocated [ver #3]

Stop the ELF-FDPIC binfmt from attempting to expand the userspace stack and brk
segments to fill the space actually allocated for it.  The space allocated may
be rounded up by mmap(), and may be wasted.

However, finding out how much space we actually obtained uses the contentious
kobjsize() function which we'd like to get rid of as it doesn't necessarily
work for all slab allocators.

Signed-off-by: David Howells <dhowells@...hat.com>
Tested-by: Mike Frysinger <vapier.adi@...il.com>
Acked-by: Paul Mundt <lethal@...ux-sh.org>
---

 fs/binfmt_elf_fdpic.c |    8 --------
 1 files changed, 0 insertions(+), 8 deletions(-)


diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c
index 22baf1b..f3e72c5 100644
--- a/fs/binfmt_elf_fdpic.c
+++ b/fs/binfmt_elf_fdpic.c
@@ -168,9 +168,6 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm,
 	struct elf_fdpic_params exec_params, interp_params;
 	struct elf_phdr *phdr;
 	unsigned long stack_size, entryaddr;
-#ifndef CONFIG_MMU
-	unsigned long fullsize;
-#endif
 #ifdef ELF_FDPIC_PLAT_INIT
 	unsigned long dynaddr;
 #endif
@@ -390,11 +387,6 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm,
 		goto error_kill;
 	}
 
-	/* expand the stack mapping to use up the entire allocation granule */
-	fullsize = kobjsize((char *) current->mm->start_brk);
-	if (!IS_ERR_VALUE(do_mremap(current->mm->start_brk, stack_size,
-				    fullsize, 0, 0)))
-		stack_size = fullsize;
 	up_write(&current->mm->mmap_sem);
 
 	current->mm->brk = current->mm->start_brk;

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/