ima: Fix a potential integer overflow in ima_appraise_measurement

[ Upstream commit d2ee2cfc4aa85ff6a2a3b198a3a524ec54e3d999 ]

When the ima-modsig is enabled, the rc passed to evm_verifyxattr() may be
negative, which may cause the integer overflow problem.

Fixes: 39b07096364a ("ima: Implement support for module-style appended signatures")
Signed-off-by: Huaxin Lu <luhuaxin1@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 3dd8c2e4314ea0f99cbc07a412f46753ddcba895..7122a359a268e98b5b598209f0e8d9d3e2fe037a 100644 (file)
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -396,7 +396,8 @@ int ima_appraise_measurement(enum ima_hooks func,
                goto out;
        }
 
-       status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value, rc, iint);
+       status = evm_verifyxattr(dentry, XATTR_NAME_IMA, xattr_value,
+                                rc < 0 ? 0 : rc, iint);
        switch (status) {
        case INTEGRITY_PASS:
        case INTEGRITY_PASS_IMMUTABLE: