2021-02-26 21:05:55

by Jeffrey Mitchell

Subject: [PATCH] ecryptfs: fix kernel panic with null dev_name

When mounting eCryptfs, a null "dev_name" argument to ecryptfs_mount()
causes a kernel panic if the parsed options are valid. The easiest way to
reproduce this is to call mount() from userspace with an existing
eCryptfs mount's options and a "source" argument of 0.

Error out if "dev_name" is null in ecryptfs_mount()

Signed-off-by: Jeffrey Mitchell <[email protected]>
---
fs/ecryptfs/main.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index e63259fdef28..b2f6a1937d23 100644
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -492,6 +492,12 @@ static struct dentry *ecryptfs_mount(struct file_system_type *fs_type, int flags
goto out;
}

+ if (!dev_name) {
+ rc = -EINVAL;
+ err = "Device name cannot be null";
+ goto out;
+ }
+
rc = ecryptfs_parse_options(sbi, raw_data, &check_ruid);
if (rc) {
err = "Error parsing options";
--
2.25.1

2021-04-19 05:52:48

by Tyler Hicks

Subject: Re: [PATCH] ecryptfs: fix kernel panic with null dev_name

On 2021-02-26 15:00:23, Jeffrey Mitchell wrote:
> When mounting eCryptfs, a null "dev_name" argument to ecryptfs_mount()
> causes a kernel panic if the parsed options are valid. The easiest way to
> reproduce this is to call mount() from userspace with an existing
> eCryptfs mount's options and a "source" argument of 0.
>
> Error out if "dev_name" is null in ecryptfs_mount()
>
> Signed-off-by: Jeffrey Mitchell <[email protected]>

Thanks for the fix! I reproduced this on a 4.15 and, while I didn't try
anything older than that, I think it affects the first kernel release
with eCryptfs. I've added the following Fixes tag:

Fixes: 237fead61998 ("[PATCH] ecryptfs: fs/Makefile and fs/Kconfig")

I've pushed it to the next branch of tyhicks/ecryptfs.git.

Tyler

> ---
> fs/ecryptfs/main.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
> index e63259fdef28..b2f6a1937d23 100644
> --- a/fs/ecryptfs/main.c
> +++ b/fs/ecryptfs/main.c
> @@ -492,6 +492,12 @@ static struct dentry *ecryptfs_mount(struct file_system_type *fs_type, int flags
> goto out;
> }
>
> + if (!dev_name) {
> + rc = -EINVAL;
> + err = "Device name cannot be null";
> + goto out;
> + }
> +
> rc = ecryptfs_parse_options(sbi, raw_data, &check_ruid);
> if (rc) {
> err = "Error parsing options";
> --
> 2.25.1
>