On Sat, Jul 07, 2007 at 02:13:01AM +0200, Jiri Kosina wrote: > On Thu, 5 Jul 2007, Rik van Riel wrote: > > > So the original patch has: > > #define BAD_ADDR(x) ((unsigned long)(x) >= TASK_SIZE) > > For some reason(?) it got changed to the clearly buggy: > > #define BAD_ADDR(x) ((unsigned long)(x) >= PAGE_MASK) > > Jiri's patch undoes that second buggy define, which is very > > different from the original that was sent in by you and Ernie. > > This is a part of execshield patch, fthe pie-compiled binary executable > memory layout randomization was extracted from - see > http://people.redhat.com/~mingo/exec-shield/exec-shield-nx-2.6.19.patch > > Note that load_elf_interp() in vanilla kernel differs from the > execshield's (and pie-randomization.patch) version. > > The fix makes the BAD_ADDR check whether the address belongs to the > ERR_PTR range, which seems valid for all uses of BAD_ADDR in the patched > binfmt_elf.c (do_brk(), elf_map(), do_mmap() etc return valid address or > err ptr) ... am I missing something obvious here?
I believe BAD_ADDR macro was changes from ((unsigned long)(x) >= TASK_SIZE) (which is the right test for invalid user addresses, stronger check than >= PAGE_MASK) to >= PAGE_MASK only because of the one check of the return value of load_elf_interp. All other uses of BAD_ADDR macro are either on userland addresses (what do_mmap, elf_map, do_brk etc. return; where TASK_SIZE or more is certainly wrong) or in one case still on unbiased ELF p_vaddr: if (BAD_ADDR(k) || elf_ppnt->p_filesz > elf_ppnt->p_memsz || in load_elf_binary (where >= TASK_SIZE check is ok too). So perhaps doing this instead of changing BAD_ADDR to IS_ERR_VAL might be better: Signed-off-by: Jakub Jelinek <[EMAIL PROTECTED]> --- linux/fs/binfmt_elf.c 2007-06-08 21:53:45.000000000 +0200 +++ linux/fs/binfmt_elf.c 2007-07-07 14:19:14.000000000 +0200 @@ -80,7 +80,7 @@ static struct linux_binfmt elf_format = .hasvdso = 1 }; -#define BAD_ADDR(x) ((unsigned long)(x) >= PAGE_MASK) +#define BAD_ADDR(x) ((unsigned long)(x) >= TASK_SIZE) static int set_brk(unsigned long start, unsigned long end) { @@ -1015,7 +1015,7 @@ static int load_elf_binary(struct linux_ interpreter, &interp_map_addr, load_bias); - if (!BAD_ADDR(elf_entry)) { + if (!IS_ERR((void *)elf_entry)) { /* load_elf_interp() returns relocation adjustment */ interp_load_addr = elf_entry; elf_entry += loc->interp_elf_ex.e_entry; Jakub - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/