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[PATCH] NFS: Fix memleak in nfs_sysfs_move_sb_to_server

Wenchao Hao posted 1 patch 2 years, 7 months ago 
fs/nfs/sysfs.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
[PATCH] NFS: Fix memleak in nfs_sysfs_move_sb_to_server
Posted by Wenchao Hao 2 years, 7 months ago 
call kfree() to free memory allocated in kasprintf() to fix
memleak. It's easy to recurrent this memleak, just mount and
remount nfs at NFS client.

The bug is detected by kmemleak with following stack:
unreferenced object 0xffffa31a91fdf2c0 (size 16):
  comm "mount.nfs", pid 960, jiffies 4294724478 (age 111892.067s)
  hex dump (first 16 bytes):
    73 65 72 76 65 72 2d 30 00 f2 fd 91 1a a3 ff ff  server-0........
  backtrace:
    [<00000000de9b21a9>] create_object+0x11/0x17
    [<00000000ed17aa96>] kmemleak_alloc+0x6c/0x7a
    [<000000009f4acc69>] slab_post_alloc_hook.constprop.0+0x81/0x99
    [<00000000d2446455>] __kmem_cache_alloc_node+0x10c/0x13a
    [<00000000eca4a704>] __kmalloc_node_track_caller+0x83/0xb7
    [<0000000076cdb22f>] kvasprintf+0x65/0xc3
    [<00000000f6f2e879>] kasprintf+0x4e/0x69
    [<00000000e49d03be>] nfs_sysfs_move_sb_to_server+0x24/0x5f
    [<0000000039127597>] nfs_kill_super+0x25/0x49
    [<00000000e6ecf809>] deactivate_locked_super+0x35/0x74
    [<000000003b9c3350>] deactivate_super+0x3c/0x44
    [<00000000777c86be>] cleanup_mnt+0x6c/0xe7
    [<000000009f181749>] __cleanup_mnt+0x12/0x18
    [<00000000a709602e>] task_work_run+0x75/0x8c
    [<0000000075da06ba>] exit_to_user_mode_prepare+0x79/0x102
    [<0000000093a53d48>] syscall_exit_to_user_mode+0x1c/0x30

Signed-off-by: Wenchao Hao <haowenchao2@huawei.com>
---
 fs/nfs/sysfs.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/nfs/sysfs.c b/fs/nfs/sysfs.c
index acda8f033d30..bf378ecd5d9f 100644
--- a/fs/nfs/sysfs.c
+++ b/fs/nfs/sysfs.c
@@ -345,8 +345,10 @@ void nfs_sysfs_move_sb_to_server(struct nfs_server *server)
 	int ret = -ENOMEM;
 
 	s = kasprintf(GFP_KERNEL, "server-%d", server->s_sysfs_id);
-	if (s)
+	if (s) {
 		ret = kobject_rename(&server->kobj, s);
+		kfree(s);
+	}
 	if (ret < 0)
 		pr_warn("NFS: rename sysfs %s failed (%d)\n",
 					server->kobj.name, ret);
-- 
2.35.3
Re: [PATCH] NFS: Fix memleak in nfs_sysfs_move_sb_to_server
Posted by Wenchao Hao 2 years, 7 months ago 
On Wed, Jul 12, 2023 at 9:48 PM Wenchao Hao <haowenchao22@gmail.com> wrote:
>
> call kfree() to free memory allocated in kasprintf() to fix
> memleak. It's easy to recurrent this memleak, just mount and
> remount nfs at NFS client.
>

I did not check the mail list before send this patch, Benjamin
Coddingto has fixed
it, so ignore this  please.

> The bug is detected by kmemleak with following stack:
> unreferenced object 0xffffa31a91fdf2c0 (size 16):
>   comm "mount.nfs", pid 960, jiffies 4294724478 (age 111892.067s)
>   hex dump (first 16 bytes):
>     73 65 72 76 65 72 2d 30 00 f2 fd 91 1a a3 ff ff  server-0........
>   backtrace:
>     [<00000000de9b21a9>] create_object+0x11/0x17
>     [<00000000ed17aa96>] kmemleak_alloc+0x6c/0x7a
>     [<000000009f4acc69>] slab_post_alloc_hook.constprop.0+0x81/0x99
>     [<00000000d2446455>] __kmem_cache_alloc_node+0x10c/0x13a
>     [<00000000eca4a704>] __kmalloc_node_track_caller+0x83/0xb7
>     [<0000000076cdb22f>] kvasprintf+0x65/0xc3
>     [<00000000f6f2e879>] kasprintf+0x4e/0x69
>     [<00000000e49d03be>] nfs_sysfs_move_sb_to_server+0x24/0x5f
>     [<0000000039127597>] nfs_kill_super+0x25/0x49
>     [<00000000e6ecf809>] deactivate_locked_super+0x35/0x74
>     [<000000003b9c3350>] deactivate_super+0x3c/0x44
>     [<00000000777c86be>] cleanup_mnt+0x6c/0xe7
>     [<000000009f181749>] __cleanup_mnt+0x12/0x18
>     [<00000000a709602e>] task_work_run+0x75/0x8c
>     [<0000000075da06ba>] exit_to_user_mode_prepare+0x79/0x102
>     [<0000000093a53d48>] syscall_exit_to_user_mode+0x1c/0x30
>
> Signed-off-by: Wenchao Hao <haowenchao2@huawei.com>
> ---
>  fs/nfs/sysfs.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/fs/nfs/sysfs.c b/fs/nfs/sysfs.c
> index acda8f033d30..bf378ecd5d9f 100644
> --- a/fs/nfs/sysfs.c
> +++ b/fs/nfs/sysfs.c
> @@ -345,8 +345,10 @@ void nfs_sysfs_move_sb_to_server(struct nfs_server *server)
>         int ret = -ENOMEM;
>
>         s = kasprintf(GFP_KERNEL, "server-%d", server->s_sysfs_id);
> -       if (s)
> +       if (s) {
>                 ret = kobject_rename(&server->kobj, s);
> +               kfree(s);
> +       }
>         if (ret < 0)
>                 pr_warn("NFS: rename sysfs %s failed (%d)\n",
>                                         server->kobj.name, ret);
> --
> 2.35.3
>
Re: [PATCH] NFS: Fix memleak in nfs_sysfs_move_sb_to_server
Posted by Ido Schimmel 2 years, 7 months ago 
On Wed, Jul 12, 2023 at 09:48:53PM +0800, Wenchao Hao wrote:
> call kfree() to free memory allocated in kasprintf() to fix
> memleak. It's easy to recurrent this memleak, just mount and
> remount nfs at NFS client.
> 
> The bug is detected by kmemleak with following stack:
> unreferenced object 0xffffa31a91fdf2c0 (size 16):
>   comm "mount.nfs", pid 960, jiffies 4294724478 (age 111892.067s)
>   hex dump (first 16 bytes):
>     73 65 72 76 65 72 2d 30 00 f2 fd 91 1a a3 ff ff  server-0........
>   backtrace:
>     [<00000000de9b21a9>] create_object+0x11/0x17
>     [<00000000ed17aa96>] kmemleak_alloc+0x6c/0x7a
>     [<000000009f4acc69>] slab_post_alloc_hook.constprop.0+0x81/0x99
>     [<00000000d2446455>] __kmem_cache_alloc_node+0x10c/0x13a
>     [<00000000eca4a704>] __kmalloc_node_track_caller+0x83/0xb7
>     [<0000000076cdb22f>] kvasprintf+0x65/0xc3
>     [<00000000f6f2e879>] kasprintf+0x4e/0x69
>     [<00000000e49d03be>] nfs_sysfs_move_sb_to_server+0x24/0x5f
>     [<0000000039127597>] nfs_kill_super+0x25/0x49
>     [<00000000e6ecf809>] deactivate_locked_super+0x35/0x74
>     [<000000003b9c3350>] deactivate_super+0x3c/0x44
>     [<00000000777c86be>] cleanup_mnt+0x6c/0xe7
>     [<000000009f181749>] __cleanup_mnt+0x12/0x18
>     [<00000000a709602e>] task_work_run+0x75/0x8c
>     [<0000000075da06ba>] exit_to_user_mode_prepare+0x79/0x102
>     [<0000000093a53d48>] syscall_exit_to_user_mode+0x1c/0x30
> 
> Signed-off-by: Wenchao Hao <haowenchao2@huawei.com>
> ---
>  fs/nfs/sysfs.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/nfs/sysfs.c b/fs/nfs/sysfs.c
> index acda8f033d30..bf378ecd5d9f 100644
> --- a/fs/nfs/sysfs.c
> +++ b/fs/nfs/sysfs.c
> @@ -345,8 +345,10 @@ void nfs_sysfs_move_sb_to_server(struct nfs_server *server)
>  	int ret = -ENOMEM;
>  
>  	s = kasprintf(GFP_KERNEL, "server-%d", server->s_sysfs_id);
> -	if (s)
> +	if (s) {
>  		ret = kobject_rename(&server->kobj, s);
> +		kfree(s);
> +	}
>  	if (ret < 0)
>  		pr_warn("NFS: rename sysfs %s failed (%d)\n",
>  					server->kobj.name, ret);

A fix was already posted:

https://lore.kernel.org/linux-nfs/6702796fee0365bf399800326bbe6c88e5f73f68.1689014440.git.bcodding@redhat.com/

Patchew 2.1-devel-b67e4c2

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