From: Xiu Jianfeng <xiujianfeng@xxxxxxxxxx>
commit 51dd64bb99e4478fc5280171acd8e1b529eadaf7 upstream.
This reverts commit ccf11dbaa07b328fa469415c362d33459c140a37.
Commit ccf11dbaa07b ("evm: Fix memleak in init_desc") said there is
memleak in init_desc. That may be incorrect, as we can see, tmp_tfm is
saved in one of the two global variables hmac_tfm or evm_tfm[hash_algo],
then if init_desc is called next time, there is no need to alloc tfm
again, so in the error path of kmalloc desc or crypto_shash_init(desc),
It is not a problem without freeing tmp_tfm.
And also that commit did not reset the global variable to NULL after
freeing tmp_tfm and this makes *tfm a dangling pointer which may cause a
UAF issue.
Reported-by: Guozihua (Scott) <guozihua@xxxxxxxxxx>
Signed-off-by: Xiu Jianfeng <xiujianfeng@xxxxxxxxxx>
Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
security/integrity/evm/evm_crypto.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
--- a/security/integrity/evm/evm_crypto.c
+++ b/security/integrity/evm/evm_crypto.c
@@ -75,7 +75,7 @@ static struct shash_desc *init_desc(char
{
long rc;
const char *algo;
- struct crypto_shash **tfm, *tmp_tfm = NULL;
+ struct crypto_shash **tfm, *tmp_tfm;
struct shash_desc *desc;
if (type == EVM_XATTR_HMAC) {
@@ -120,16 +120,13 @@ unlock:
alloc:
desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(*tfm),
GFP_KERNEL);
- if (!desc) {
- crypto_free_shash(tmp_tfm);
+ if (!desc)
return ERR_PTR(-ENOMEM);
- }
desc->tfm = *tfm;
rc = crypto_shash_init(desc);
if (rc) {
- crypto_free_shash(tmp_tfm);
kfree(desc);
return ERR_PTR(rc);
}
