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

[Jinjie Ruan <ruanjinjie@huawei.com>]

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@gmail.com/
> 
> 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.

> 
> 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@linux-foundation.org>
>> Cc: Baoquan He <bhe@redhat.com>
>> Cc: Mike Rapoport <rppt@kernel.org>
>> Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
>> Cc: Pratyush Yadav <pratyush@kernel.org>
>> Cc: Dave Young <ruirui.yang@linux.dev>
>> Cc: stable@vger.kernel.org
>> Fixes: e3a84be1ec2f ("arm64,ppc64le/kdump: pass dm-crypt keys to kdump
>> kernel")
>> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
>> ---
>>   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;
>