Re: [PATCH v3 07/17] crash_dump: Fix potential double-free of keys_header

[Coiby Xu]

On Mon, Aug 31, 2026 at 09:24:07AM +0800, Jinjie Ruan wrote:
> 在 2026/8/30 13:59, Sourabh Jain 写道:
> > Hello Jinjie,
> >
> > Coiby is handling this issue in the below patch series:
> > https://lore.kernel.org/all/20260828084900.1496839-2-coiby.xu@xxxxxxxxx/
> >
> > Since the above patch series is all about crash_load_dm_crypt_keys,
> > could you
> > please consider dropping this patch from your series and reviewing his
> > patch
> > instead?
>
> Absolutely, happy to do so — I'll drop this patch and review Coiby's
> series instead.

Hi Jinjie,

Thank you for agreeing to drop your patch and review mine instead!

> > Thanks,
> > Sourabh Jain
> >
> > On 26/08/26 14:55, Jinjie Ruan wrote:
> > > `keys_header` was freed in `build_keys_header()` without being reset
> > > to NULL, and the error path in `crash_load_dm_crypt_keys()` freed it
> > > unconditionally even when reused, leading to double-free or
> > > use-after-free.
> > >
> > > Add `free_keys_header()` to centralize freeing and NULL-setting.
> > > Use it in `build_keys_header()` and only free in the error path when
> > > the header was newly built (`!is_dm_key_reused`).
> > >
> > > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > > Cc: Baoquan He <bhe@xxxxxxxxxx>
> > > Cc: Mike Rapoport <rppt@xxxxxxxxxx>
> > > Cc: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
> > > Cc: Pratyush Yadav <pratyush@xxxxxxxxxx>
> > > Cc: Dave Young <ruirui.yang@xxxxxxxxx>
> > > Cc: stable@xxxxxxxxxxxxxxx
> > > Fixes: e3a84be1ec2f ("arm64,ppc64le/kdump: pass dm-crypt keys to kdump
> > > kernel")
> > > Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
> > > ---
> > >   kernel/crash_dump_dm_crypt.c | 15 +++++++++++----
> > >   1 file changed, 11 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/kernel/crash_dump_dm_crypt.c b/kernel/crash_dump_dm_crypt.c
> > > index c685497cd470..ed0960ff0987 100644
> > > --- a/kernel/crash_dump_dm_crypt.c
> > > +++ b/kernel/crash_dump_dm_crypt.c
> > > @@ -363,15 +363,21 @@ static struct configfs_subsystem
> > > config_keys_subsys = {
> > >       },
> > >   };
> > >   +static void free_keys_header(void)
> > > +{
> > > +    if (keys_header) {
> > > +        kvfree(keys_header);
> > > +        keys_header = NULL;
> > > +    }
> > > +}
> > > +
> > >   static int build_keys_header(void)
> > >   {
> > >       struct config_item *item = NULL;
> > >       struct config_key *key;
> > >       int i, r;
> > >   -    if (keys_header != NULL)
> > > -        kvfree(keys_header);
> > > -
> > > +    free_keys_header();
> > >       keys_header = kzalloc(get_keys_header_size(key_count), GFP_KERNEL);
> > >       if (!keys_header)
> > >           return -ENOMEM;
> > > @@ -441,7 +447,8 @@ int crash_load_dm_crypt_keys(struct kimage *image)
> > >       r = kexec_add_buffer(&kbuf);
> > >       if (r) {
> > >           pr_err("Failed to call kexec_add_buffer, ret=%d\n", r);
> > > -        kvfree((void *)kbuf.buffer);
> > > +        if (!is_dm_key_reused)
> > > +            free_keys_header();
> > >           return r;
> > >       }
> > >       image->dm_crypt_keys_addr = kbuf.mem;

--
Best regards,
Coiby