2022-02-03 08:38:53

by Mike Rapoport

Subject: [PATCH] fs/binfmt_elf: fix PT_LOAD p_align values for loaders

From: Mike Rapoport <[email protected]>

Rui Salvaterra reported that Aisleroit solitaire crashes with "Wrong
__data_start/_end pair" assertion from libgc after update to v5.17-rc1.

Bisection pointed to commit 9630f0d60fec ("fs/binfmt_elf: use PT_LOAD
p_align values for static PIE") that fixed handling of static PIEs, but
made the condition that guards load_bias calculation to exclude loader
binaries.

Restoring the check for presence of interpreter fixes the problem.

Fixes: 9630f0d60fec ("fs/binfmt_elf: use PT_LOAD p_align values for static PIE")
Reported-by: Rui Salvaterra <[email protected]>
Signed-off-by: Mike Rapoport <[email protected]>
---
fs/binfmt_elf.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 605017eb9349..9e11e6f13e83 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1117,7 +1117,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
* without MAP_FIXED nor MAP_FIXED_NOREPLACE).
*/
alignment = maximum_alignment(elf_phdata, elf_ex->e_phnum);
- if (alignment > ELF_MIN_ALIGN) {
+ if (interpreter || alignment > ELF_MIN_ALIGN) {
load_bias = ELF_ET_DYN_BASE;
if (current->flags & PF_RANDOMIZE)
load_bias += arch_mmap_rnd();
--
2.34.1

2022-02-03 12:09:16

by Rui Salvaterra

Subject: Re: [PATCH] fs/binfmt_elf: fix PT_LOAD p_align values for loaders

Hi, Mike,

On Wed, 2 Feb 2022 at 12:14, Mike Rapoport <[email protected]> wrote:
>
> From: Mike Rapoport <[email protected]>
>
> Rui Salvaterra reported that Aisleroit solitaire crashes with "Wrong
> __data_start/_end pair" assertion from libgc after update to v5.17-rc1.
>
> Bisection pointed to commit 9630f0d60fec ("fs/binfmt_elf: use PT_LOAD
> p_align values for static PIE") that fixed handling of static PIEs, but
> made the condition that guards load_bias calculation to exclude loader
> binaries.
>
> Restoring the check for presence of interpreter fixes the problem.
>
> Fixes: 9630f0d60fec ("fs/binfmt_elf: use PT_LOAD p_align values for static PIE")
> Reported-by: Rui Salvaterra <[email protected]>
> Signed-off-by: Mike Rapoport <[email protected]>
> ---
> fs/binfmt_elf.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
> index 605017eb9349..9e11e6f13e83 100644
> --- a/fs/binfmt_elf.c
> +++ b/fs/binfmt_elf.c
> @@ -1117,7 +1117,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
> * without MAP_FIXED nor MAP_FIXED_NOREPLACE).
> */
> alignment = maximum_alignment(elf_phdata, elf_ex->e_phnum);
> - if (alignment > ELF_MIN_ALIGN) {
> + if (interpreter || alignment > ELF_MIN_ALIGN) {
> load_bias = ELF_ET_DYN_BASE;
> if (current->flags & PF_RANDOMIZE)
> load_bias += arch_mmap_rnd();
> --
> 2.34.1
>

The patch does fix the problem for me, and is thus

Tested-by: Rui Salvaterra <[email protected]>

Thanks,
Rui