ima: Fix use after free in ima_read_modsig()

If we can't parse the PKCS7 in the appended modsig, we will free the modsig structure and then access one of its members to determine the error value. Fixes: 39b0709 ("ima: Implement support for module-style appended signatures") Reported-by: kbuild test robot <[email protected]> Reported-by: Julia Lawall <[email protected]> Reported-by: Dan Carpenter <[email protected]> Signed-off-by: Thiago Jung Bauermann <[email protected]> Reviewed-by: Gustavo A. R. Silva <[email protected]> Signed-off-by: Mimi Zohar <[email protected]>
fracktal · Aug 28, 2019 · 556d971 · 556d971
1 parent 70433f6
commit 556d971
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/security/integrity/ima/ima_modsig.c b/security/integrity/ima/ima_modsig.c
@@ -91,8 +91,9 @@ int ima_read_modsig(enum ima_hooks func, const void *buf, loff_t buf_len,
 
 	hdr->pkcs7_msg = pkcs7_parse_message(buf + buf_len, sig_len);
 	if (IS_ERR(hdr->pkcs7_msg)) {
+		rc = PTR_ERR(hdr->pkcs7_msg);
 		kfree(hdr);
-		return PTR_ERR(hdr->pkcs7_msg);
+		return rc;
 	}
 
 	memcpy(hdr->raw_pkcs7, buf + buf_len, sig_len);