Techwizz/kernel-fxtec-pro1x
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

fs/binfmt_elf_fdpic.c: fix brk area overlap with stack on NOMMU

Browse source 
On NOMMU archs, the FDPIC ELF loader sets up the usable brk range to
overlap with all but the last PAGE_SIZE bytes of the stack. This leads
to catastrophic memory reuse/corruption if brk is used. Fix by setting
the brk area to zero size to disable its use.

Signed-off-by: Rich Felker <dalias@libc.org>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
This commit is contained in:
Rich Felker 2015-08-20 15:11:06 -04:00 committed by Greg Ungerer
parent 32b88194f7
commit 4ac3131110
1 changed files with 1 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

7
fs/binfmt_elf_fdpic.c
View file

@ -374,10 +374,7 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm)
PAGE_ALIGN(current->mm->start_brk);
#else
/* create a stack and brk area big enough for everyone
* - the brk heap starts at the bottom and works up
* - the stack starts at the top and works down
*/
/* create a stack area and zero-size brk area */
stack_size = (stack_size + PAGE_SIZE - 1) & PAGE_MASK;
if (stack_size < PAGE_SIZE * 2)
stack_size = PAGE_SIZE * 2;
@ -400,8 +397,6 @@ static int load_elf_fdpic_binary(struct linux_binprm *bprm)
current->mm->brk = current->mm->start_brk;
current->mm->context.end_brk = current->mm->start_brk;
current->mm->context.end_brk +=
(stack_size > PAGE_SIZE) ? (stack_size - PAGE_SIZE) : 0;
current->mm->start_stack = current->mm->start_brk + stack_size;
#endif