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    Subject[PATCH 5.9 60/74] evm: Check size of security.evm before using it
    Date
    From: Roberto Sassu <roberto.sassu@huawei.com>

    commit 455b6c9112eff8d249e32ba165742085678a80a4 upstream.

    This patch checks the size for the EVM_IMA_XATTR_DIGSIG and
    EVM_XATTR_PORTABLE_DIGSIG types to ensure that the algorithm is read from
    the buffer returned by vfs_getxattr_alloc().

    Cc: stable@vger.kernel.org # 4.19.x
    Fixes: 5feeb61183dde ("evm: Allow non-SHA1 digital signatures")
    Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
    Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    security/integrity/evm/evm_main.c | 6 ++++++
    1 file changed, 6 insertions(+)

    --- a/security/integrity/evm/evm_main.c
    +++ b/security/integrity/evm/evm_main.c
    @@ -181,6 +181,12 @@ static enum integrity_status evm_verify_
    break;
    case EVM_IMA_XATTR_DIGSIG:
    case EVM_XATTR_PORTABLE_DIGSIG:
    + /* accept xattr with non-empty signature field */
    + if (xattr_len <= sizeof(struct signature_v2_hdr)) {
    + evm_status = INTEGRITY_FAIL;
    + goto out;
    + }
    +
    hdr = (struct signature_v2_hdr *)xattr_data;
    digest.hdr.algo = hdr->hash_algo;
    rc = evm_calc_hash(dentry, xattr_name, xattr_value,

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