From: Xiu Jianfeng <xiujianfeng@huawei.com> stable inclusion from stable-v5.10.132 commit 9d883b3f000d405d19b3484e3d8d97796e6854c6 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5YS3T Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- 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@huawei.com> Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Conflicts: security/integrity/evm/evm_crypto.c Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Acked-by: Xie XiuQi <xiexiuqi@huawei.com> --- 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 01aa74e9bebf..7c36dbb96d24 100644 --- a/security/integrity/evm/evm_crypto.c +++ b/security/integrity/evm/evm_crypto.c @@ -73,7 +73,7 @@ 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; char evm_hmac[CRYPTO_MAX_ALG_NAME]; struct shash_desc *desc; @@ -122,16 +122,13 @@ 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); } -- 2.20.1