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| author | Eric Biggers <ebiggers@google.com> | 2022-10-12 00:38:38 +0300 |
|---|---|---|
| committer | Eric Biggers <ebiggers@google.com> | 2022-10-20 06:54:43 +0300 |
| commit | ccd30a476f8e864732de220bd50e6f372f5ebcab (patch) | |
| tree | f5a57819df1068b8d13c5a897bb2b94b47890466 /fs | |
| parent | 9abf2313adc1ca1b6180c508c25f22f9395cc780 (diff) | |
| download | linux-ccd30a476f8e864732de220bd50e6f372f5ebcab.tar.xz | |
fscrypt: fix keyring memory leak on mount failure
Commit d7e7b9af104c ("fscrypt: stop using keyrings subsystem for
fscrypt_master_key") moved the keyring destruction from __put_super() to
generic_shutdown_super() so that the filesystem's block device(s) are
still available. Unfortunately, this causes a memory leak in the case
where a mount is attempted with the test_dummy_encryption mount option,
but the mount fails after the option has already been processed.
To fix this, attempt the keyring destruction in both places.
Reported-by: syzbot+104c2a89561289cec13e@syzkaller.appspotmail.com
Fixes: d7e7b9af104c ("fscrypt: stop using keyrings subsystem for fscrypt_master_key")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Link: https://lore.kernel.org/r/20221011213838.209879-1-ebiggers@kernel.org
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/crypto/keyring.c | 17 | ||||
| -rw-r--r-- | fs/super.c | 3 |
2 files changed, 13 insertions, 7 deletions
diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c index 1cca09aa43f8..2a24b1f0ae68 100644 --- a/fs/crypto/keyring.c +++ b/fs/crypto/keyring.c @@ -205,14 +205,19 @@ static int allocate_filesystem_keyring(struct super_block *sb) } /* - * This is called at unmount time to release all encryption keys that have been - * added to the filesystem, along with the keyring that contains them. + * Release all encryption keys that have been added to the filesystem, along + * with the keyring that contains them. * - * Note that besides clearing and freeing memory, this might need to evict keys - * from the keyslots of an inline crypto engine. Therefore, this must be called - * while the filesystem's underlying block device(s) are still available. + * This is called at unmount time. The filesystem's underlying block device(s) + * are still available at this time; this is important because after user file + * accesses have been allowed, this function may need to evict keys from the + * keyslots of an inline crypto engine, which requires the block device(s). + * + * This is also called when the super_block is being freed. This is needed to + * avoid a memory leak if mounting fails after the "test_dummy_encryption" + * option was processed, as in that case the unmount-time call isn't made. */ -void fscrypt_sb_delete(struct super_block *sb) +void fscrypt_destroy_keyring(struct super_block *sb) { struct fscrypt_keyring *keyring = sb->s_master_keys; size_t i; diff --git a/fs/super.c b/fs/super.c index 6a82660e1adb..8d39e4f11cfa 100644 --- a/fs/super.c +++ b/fs/super.c @@ -291,6 +291,7 @@ static void __put_super(struct super_block *s) WARN_ON(s->s_inode_lru.node); WARN_ON(!list_empty(&s->s_mounts)); security_sb_free(s); + fscrypt_destroy_keyring(s); put_user_ns(s->s_user_ns); kfree(s->s_subtype); call_rcu(&s->rcu, destroy_super_rcu); @@ -479,7 +480,7 @@ void generic_shutdown_super(struct super_block *sb) evict_inodes(sb); /* only nonzero refcount inodes can have marks */ fsnotify_sb_delete(sb); - fscrypt_sb_delete(sb); + fscrypt_destroy_keyring(sb); security_sb_delete(sb); if (sb->s_dio_done_wq) { |