struct evm_xattr is only used for EVM_XATTR_HMAC type evm digest and glues together one flexible array and one fixed length array. The original intention might be shortening the code as the "data" field would always be a SHA1 digest. This implementation is not complying with GCC's specification about flexible array which requires that flexible should be the last member of a structure and structure of flexible array should not be a sub structure. Fix it by: 1. Remove struct evm_xattr and use struct evm_ima_xattr_data directly. 2. Get array size with struct_size instead of sizeof as suggested by Linus. Reference: https://lore.kernel.org/all/CAHk-=wiGWjxs7EVUpccZEi6esvjpHJdgHQ=vtUeJ5crL62hx9A@xxxxxxxxxxxxxx/ Fixes: 6be5cc5246f80 ("evm: add support for different security.evm data types") Signed-off-by: GUO Zihua <guozihua@xxxxxxxxxx> --- v2: Change the patch subject to PATCH instead of PATCH -next. Update commit message based on feedback from Gustavo on another patch. --- security/integrity/evm/evm_main.c | 14 ++++++++------ security/integrity/integrity.h | 6 ------ 2 files changed, 8 insertions(+), 12 deletions(-) diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index 7d87772f0ce6..f2c4501a287a 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -211,7 +211,8 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, /* check value type */ switch (xattr_data->type) { case EVM_XATTR_HMAC: - if (xattr_len != sizeof(struct evm_xattr)) { + if (xattr_len != struct_size(*xattr_data, data, + SHA1_DIGEST_SIZE)) { evm_status = INTEGRITY_FAIL; goto out; } @@ -842,24 +843,25 @@ int evm_inode_init_security(struct inode *inode, const struct xattr *lsm_xattr, struct xattr *evm_xattr) { - struct evm_xattr *xattr_data; + struct evm_ima_xattr_data *xattr_data; int rc; if (!(evm_initialized & EVM_INIT_HMAC) || !evm_protected_xattr(lsm_xattr->name)) return 0; - xattr_data = kzalloc(sizeof(*xattr_data), GFP_NOFS); + xattr_data = kzalloc(struct_size(*xattr_data, data, + SHA1_DIGEST_SIZE), GFP_NOFS); if (!xattr_data) return -ENOMEM; - xattr_data->data.type = EVM_XATTR_HMAC; - rc = evm_init_hmac(inode, lsm_xattr, xattr_data->digest); + xattr_data->type = EVM_XATTR_HMAC; + rc = evm_init_hmac(inode, lsm_xattr, xattr_data->data); if (rc < 0) goto out; evm_xattr->value = xattr_data; - evm_xattr->value_len = sizeof(*xattr_data); + evm_xattr->value_len = struct_size(*xattr_data, data, SHA1_DIGEST_SIZE); evm_xattr->name = XATTR_EVM_SUFFIX; return 0; out: diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h index 3510e413ea17..91b16d620dd9 100644 --- a/security/integrity/integrity.h +++ b/security/integrity/integrity.h @@ -86,12 +86,6 @@ struct evm_ima_xattr_data { u8 data[]; } __packed; -/* Only used in the EVM HMAC code. */ -struct evm_xattr { - struct evm_ima_xattr_data data; - u8 digest[SHA1_DIGEST_SIZE]; -} __packed; - #define IMA_MAX_DIGEST_SIZE 64 struct ima_digest_data { -- 2.36.0
