[PATCH] eCryptfs: use after free in ecryptfs_release_messaging()

[PATCH] eCryptfs: use after free in ecryptfs_release_messaging()

[Dan Carpenter]

We're freeing the list iterator so we should be using the _safe()
version of hlist_for_each_entry().

Fixes: 88b4a07e6610 ("[PATCH] eCryptfs: Public key transport mechanism")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
It's also possible that I misunderstood this code.  Please review with
caution.

diff --git a/fs/ecryptfs/messaging.c b/fs/ecryptfs/messaging.c
index 286f10b0363b..4f457d5c4933 100644
--- a/fs/ecryptfs/messaging.c
+++ b/fs/ecryptfs/messaging.c
@@ -442,15 +442,16 @@ void ecryptfs_release_messaging(void)
 	}
 	if (ecryptfs_daemon_hash) {
 		struct ecryptfs_daemon *daemon;
+		struct hlist_node *n;
 		int i;
 
 		mutex_lock(&ecryptfs_daemon_hash_mux);
 		for (i = 0; i < (1 << ecryptfs_hash_bits); i++) {
 			int rc;
 
-			hlist_for_each_entry(daemon,
-					     &ecryptfs_daemon_hash[i],
-					     euid_chain) {
+			hlist_for_each_entry_safe(daemon, n,
+						  &ecryptfs_daemon_hash[i],
+						  euid_chain) {
 				rc = ecryptfs_exorcise_daemon(daemon);
 				if (rc)
 					printk(KERN_ERR "%s: Error whilst "

Re: [PATCH] eCryptfs: use after free in ecryptfs_release_messaging()

[Tyler Hicks]

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Hi Dan - Thanks for the patch. I'm sorry for not getting back to you
until now.

On 08/22/2017 04:41 PM, Dan Carpenter wrote:
> We're freeing the list iterator so we should be using the _safe()
> version of hlist_for_each_entry().
> 
> Fixes: 88b4a07e6610 ("[PATCH] eCryptfs: Public key transport mechanism")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

I think this patch is correct. I'll perform some testing and, if all
goes well, get it in before 4.14 is released.

Tyler

> ---
> It's also possible that I misunderstood this code.  Please review with
> caution.
> 
> diff --git a/fs/ecryptfs/messaging.c b/fs/ecryptfs/messaging.c
> index 286f10b0363b..4f457d5c4933 100644
> --- a/fs/ecryptfs/messaging.c
> +++ b/fs/ecryptfs/messaging.c
> @@ -442,15 +442,16 @@ void ecryptfs_release_messaging(void)
>  	}
>  	if (ecryptfs_daemon_hash) {
>  		struct ecryptfs_daemon *daemon;
> +		struct hlist_node *n;
>  		int i;
>  
>  		mutex_lock(&ecryptfs_daemon_hash_mux);
>  		for (i = 0; i < (1 << ecryptfs_hash_bits); i++) {
>  			int rc;
>  
> -			hlist_for_each_entry(daemon,
> -					     &ecryptfs_daemon_hash[i],
> -					     euid_chain) {
> +			hlist_for_each_entry_safe(daemon, n,
> +						  &ecryptfs_daemon_hash[i],
> +						  euid_chain) {
>  				rc = ecryptfs_exorcise_daemon(daemon);
>  				if (rc)
>  					printk(KERN_ERR "%s: Error whilst "
> --
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> 



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