Re: [PATCH next] binfmt_elf: Fix potential Oops in load_elf_binary()
From: Jan Kara
Date: Wed Dec 11 2024 - 11:48:46 EST
On Wed 11-12-24 12:21:39, Dan Carpenter wrote:
> This function call was changed from allow_write_access() which has a NULL
> check to exe_file_allow_write_access() which doesn't. Check for NULL
> before calling it.
>
> Fixes: 871387b27c20 ("fs: don't block write during exec on pre-content watched files")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Thanks for noticing! I've opted to change exe_file_allow_write_access() to
check for NULL instead to be 1:1 replacement for allow_write_access().
Because bugs like this one are very easy to introduce.
Honza
> ---
> fs/binfmt_elf.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
> index 8054f44d39cf..db9cb4c20125 100644
> --- a/fs/binfmt_elf.c
> +++ b/fs/binfmt_elf.c
> @@ -1354,9 +1354,10 @@ static int load_elf_binary(struct linux_binprm *bprm)
> kfree(interp_elf_ex);
> kfree(interp_elf_phdata);
> out_free_file:
> - exe_file_allow_write_access(interpreter);
> - if (interpreter)
> + if (interpreter) {
> + exe_file_allow_write_access(interpreter);
> fput(interpreter);
> + }
> out_free_ph:
> kfree(elf_phdata);
> goto out;
> --
> 2.45.2
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR