| Message ID | 20220527111726.195825-1-xiujianfeng@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [-next] Revert "evm: Fix memleak in init_desc" | expand |
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@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 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); > }
On Fri, 2022-05-27 at 19:17 +0800, Xiu Jianfeng wrote: > 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 ohr 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@huawei.com> Agreed, thanks. This was first reported by Guozihua (Scott) < guozihua@huawei.com>. If neither you nor Scott object, I'll add his Reported-by tag. thanks, Mimi
On 2022/6/10 22:20, Mimi Zohar wrote: > On Fri, 2022-05-27 at 19:17 +0800, Xiu Jianfeng wrote: >> 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 ohr 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@huawei.com> > > Agreed, thanks. This was first reported by Guozihua (Scott) < > guozihua@huawei.com>. If neither you nor Scott object, I'll add his > Reported-by tag. > > thanks, > > Mimi > > . Good for me.
在 2022/6/10 22:20, Mimi Zohar 写道: > On Fri, 2022-05-27 at 19:17 +0800, Xiu Jianfeng wrote: >> 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 ohr 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@huawei.com> > Agreed, thanks. This was first reported by Guozihua (Scott) < > guozihua@huawei.com>. If neither you nor Scott object, I'll add his > Reported-by tag. Good for me, thanks. > > thanks, > > Mimi > > > > > > .
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); }
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@huawei.com> --- security/integrity/evm/evm_crypto.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-)