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crash_dump: fix dm_crypt keys locking and ref leak

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crash_load_dm_crypt_keys() reads dm-crypt volume keys from the user
keyring.  It uses user_key_payload_locked() without holding key->sem,
which makes lockdep complain when kexec_file_load() assembles the crash
image:

  =============================
  WARNING: suspicious RCU usage
  -----------------------------
  ./include/keys/user-type.h:53 suspicious rcu_dereference_protected() usage!

  other info that might help us debug this:

  rcu_scheduler_active = 2, debug_locks = 1
  no locks held by kexec/4875.

  stack backtrace:
  Call Trace:
   <TASK>
   dump_stack_lvl+0x5d/0x80
   lockdep_rcu_suspicious.cold+0x4e/0x96
   crash_load_dm_crypt_keys+0x314/0x390
   bzImage64_load+0x116/0x9a0
   ? __lock_acquire+0x464/0x1ba0
   __do_sys_kexec_file_load+0x26a/0x4f0
   do_syscall_64+0xbd/0x430
   entry_SYSCALL_64_after_hwframe+0x77/0x7f

In addition, the key returned by request_key() is never key_put()'d,
leaking a key reference on each load attempt.

Take key->sem while copying the payload and drop the key reference
afterwards.

Link: https://lkml.kernel.org/r/patch.git-2d4d76083a5c.your-ad-here.call-01769426386-ext-2560@work.hours
Fixes: 479e58549b ("crash_dump: store dm crypt keys in kdump reserved memory")
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Coiby Xu <coxu@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Vasily Gorbik
2026-01-26 12:20:46 +01:00
committed by Andrew Morton
parent b50634c5e8
commit 96a54b8ffc
1 changed files with 13 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
kernel/crash_dump_dm_crypt.c
View File

@@ -143,6 +143,7 @@ static int read_key_from_user_keying(struct dm_crypt_key *dm_key)
{
const struct user_key_payload *ukp;
struct key *key;
int ret = 0;
kexec_dprintk("Requesting logon key %s", dm_key->key_desc);
key = request_key(&key_type_logon, dm_key->key_desc, NULL);
@@ -152,20 +153,28 @@ static int read_key_from_user_keying(struct dm_crypt_key *dm_key)
return PTR_ERR(key);
}
down_read(&key->sem);
ukp = user_key_payload_locked(key);
if (!ukp)
return -EKEYREVOKED;
if (!ukp) {
ret = -EKEYREVOKED;
goto out;
}
if (ukp->datalen > KEY_SIZE_MAX) {
pr_err("Key size %u exceeds maximum (%u)\n", ukp->datalen, KEY_SIZE_MAX);
return -EINVAL;
ret = -EINVAL;
goto out;
}
memcpy(dm_key->data, ukp->data, ukp->datalen);
dm_key->key_size = ukp->datalen;
kexec_dprintk("Get dm crypt key (size=%u) %s: %8ph\n", dm_key->key_size,
dm_key->key_desc, dm_key->data);
return 0;
out:
up_read(&key->sem);
key_put(key);
return ret;
}
struct config_key {