Messages in this thread | | | Date | Sat, 06 Mar 2004 22:11:18 -0800 | From | Ulrich Drepper <> | Subject | Re: Potential bug in fs/binfmt_elf.c? |
| |
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1
Mike Hearn wrote:
> LOAD 0x000000 0x00000000 0x00000000 0x00bc4 0x00bc4 R E 0x1000 > LOAD 0x000bc4 0x00000bc4 0x00000bc4 0x00150 0x00154 RW 0x1000 > DYNAMIC 0x000bd0 0x00000bd0 0x00000bd0 0x00108 0x00108 RW 0x4 > LOAD 0x001000 0x00400000 0x00400000 0x00000 0x10000000 R 0x1000
Not everything which can be expressed in ELF is supported. You don't want to load something, you want to reserve address space. And you want it allocated in a certain way. The ELF loader is no generic ELF interpreter.
Now, if the only problem is the overcommit and making the do_brk() call allocate the memory as read-only a change to the do_brk() interface might be acceptable (well, ask somebody doing mm hacking). I wouldn't be entirely sure whether read-only pages alone are enough. This does not open any new holes as far as I can see.
I'd say experiment with it and add a flags parameter which is the right combination of VM_READ | VM_WRITE | VM_EXEC. All calls but the one in binfmt_elf.c should pass all read bits, the one in binfmt_elf can respect the binaries flags. You must be sure, though, that the last page of the data area (i.e., writable area) in a regular binary is not mapped read-only.
- -- ➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.3 (GNU/Linux)
iD8DBQFASr0L2ijCOnn/RHQRAjtZAJ931c+0Czw8jJc0kOv1+lIMyVLEOgCgtj3f aHnlBUWz8qFQitDqVBWyPpc= =f2UN -----END PGP SIGNATURE----- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |