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authorRoberto Sassu <roberto.sassu@huawei.com>2020-09-04 11:23:30 +0200
committerMimi Zohar <zohar@linux.ibm.com>2020-09-15 13:47:42 -0400
commit455b6c9112eff8d249e32ba165742085678a80a4 (patch)
treefaed71382cd53d9bcd78a58328cdb1430c67b64c /security
parent4be92db3b5667f3a5c874a04635b037dc5e3f373 (diff)
evm: Check size of security.evm before using it
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>
Diffstat (limited to 'security')
-rw-r--r--security/integrity/evm/evm_main.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c
index 6ae00fee1d34..76d19146d74b 100644
--- a/security/integrity/evm/evm_main.c
+++ b/security/integrity/evm/evm_main.c
@@ -184,6 +184,12 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry,
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,