Hi, ping.... 在 2022/5/27 19:17, Xiu Jianfeng 写道:
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. Signed-off-by: Xiu Jianfeng <xiujianfeng@xxxxxxxxxx> --- security/integrity/evm/evm_crypto.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c index a733aff02006..708de9656bbd 100644 --- 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 type, uint8_t hash_algo) { 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 @@ static struct shash_desc *init_desc(char type, uint8_t hash_algo) 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); }
