On Thu, Jul 05, 2018 at 09:18:08AM +0200, Oscar Salvador wrote:
> > So, indeed "bss" needs to be aligned.
> > But ELF_PAGESTART() or ELF_PAGEALIGN(), which one to use?
> >
> > #define ELF_PAGESTART(_v) ((_v) & ~(unsigned long)(ELF_MIN_ALIGN-1))
> > #define ELF_PAGEALIGN(_v) (((_v) + ELF_MIN_ALIGN - 1) & ~(ELF_MIN_ALIGN - 1))
> >
> > Is
> >
> > - len = ELF_PAGESTART(eppnt->p_filesz + eppnt->p_vaddr +
> > - ELF_MIN_ALIGN - 1);
> > + len = ELF_PAGEALIGN(eppnt->p_filesz + eppnt->p_vaddr);
> >
> > suggesting that
> >
> > - bss = eppnt->p_memsz + eppnt->p_vaddr;
> > + bss = ELF_PAGEALIGN(eppnt->p_memsz + eppnt->p_vaddr);
> >
> > is the right choice? I don't know...
>
> Yes, I think that ELF_PAGEALIGN is the right choice here.
> Given that bss is 0x7bf88676, using ELF_PAGESTART aligns it but backwards, while ELF_PAGEALIGN does
> the right thing:
>
> bss = 0x7bf88676
> ELF_PAGESTART (bss) = 0x7bf88000
> ELF_PAGEALIGN (bss) = 0x7bf89000
I think this should do the trick:
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 0ac456b52bdd..6c7e005ae12d 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1259,9 +1259,9 @@ 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)
I could only test it in x86_64 (with -m32).
Could you test it on x86_32?
--
Oscar Salvador
SUSE L3
