v4: - Remove the __user annotation from big_key_read() and user_read() in patch 1. - Add a new patch 2 to remove __user annotation from rxrpc_read(). - Add a new patch 3 to remove __user annotation from dns_resolver_read(). - Merge the original patches 2 and 3 into a single patch 4 and refactor it as suggested by Jarkko and Eric. v3: - Reorganize the keyctl_read_key() code to make it more readable as suggested by Jarkko Sakkinen. - Add patch 3 to use kvmalloc() for safer large buffer allocation as suggested by David Howells. v2: - Handle NULL buffer and buflen properly in patch 1. - Fix a bug in big_key.c. - Add patch 2 to handle arbitrary large user-supplied buflen. The current security key read methods are called with the key semaphore held. The methods then copy out the key data to userspace which is subjected to page fault and may acquire the mmap semaphore. That can result in circular lock dependency and hence a chance to get into deadlock. To avoid such a deadlock, an internal buffer is now allocated for getting out the necessary data first. After releasing the key semaphore, the key data are then copied out to userspace sidestepping the circular lock dependency. The keyutils test suite was run and the test passed with these patchset applied without any falure. Waiman Long (4): KEYS: Don't write out to userspace while holding key semaphore KEYS: Remove __user annotation from rxrpc_read() KEYS: Remove __user annotation from dns_resolver_read() KEYS: Avoid false positive ENOMEM error on key read include/keys/big_key-type.h | 2 +- include/keys/user-type.h | 3 +- include/linux/key-type.h | 2 +- net/dns_resolver/dns_key.c | 2 +- net/rxrpc/key.c | 27 +++---- security/keys/big_key.c | 11 ++- security/keys/encrypted-keys/encrypted.c | 7 +- security/keys/internal.h | 12 ++++ security/keys/keyctl.c | 86 ++++++++++++++++++++--- security/keys/keyring.c | 6 +- security/keys/request_key_auth.c | 7 +- security/keys/trusted-keys/trusted_tpm1.c | 14 +--- security/keys/user_defined.c | 5 +- 13 files changed, 116 insertions(+), 68 deletions(-) -- 2.18.1
