From: Steve French <smfrench@gmail.com>
To: Eugene Korenevsky <ekorenevsky@astralinux.ru>
Cc: CIFS <linux-cifs@vger.kernel.org>
Subject: Re: [PATCH] cifs: fix out-of-bound memory access when calling smb3_notify() at mount point
Date: Sat, 17 Apr 2021 15:05:02 -0500 [thread overview]
Message-ID: <CAH2r5muwTAmOQ69GRQJgw7uVsqp0z7yi+1jBhjrk8=L5-24HiA@mail.gmail.com> (raw)
In-Reply-To: <20210416073530.GA21974@himera.home>
Added:
CC: <stable@vger.kernel.org> # v5.6+
and merged into cifs-2.6.git for-next
On Fri, Apr 16, 2021 at 2:42 AM Eugene Korenevsky
<ekorenevsky@astralinux.ru> wrote:
>
> If smb3_notify() is called at mount point of CIFS, build_path_from_dentry()
> returns the pointer to kmalloc-ed memory with terminating zero (this is
> empty FileName to be passed to SMB2 CREATE request). This pointer is assigned
> to the `path` variable.
> Then `path + 1` (to skip first backslash symbol) is passed to
> cifs_convert_path_to_utf16(). This is incorrect for empty path and causes
> out-of-bound memory access.
>
> Get rid of this "increase by one". cifs_convert_path_to_utf16() already
> contains the check for leading backslash in the path.
>
> BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=212693
> Signed-off-by: Eugene Korenevsky <ekorenevsky@astralinux.ru>
> ---
> fs/cifs/smb2ops.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
> index caa5432a5ed1..b13a8e3e1e24 100644
> --- a/fs/cifs/smb2ops.c
> +++ b/fs/cifs/smb2ops.c
> @@ -2264,7 +2264,7 @@ smb3_notify(const unsigned int xid, struct file *pfile,
> goto notify_exit;
> }
>
> - utf16_path = cifs_convert_path_to_utf16(path + 1, cifs_sb);
> + utf16_path = cifs_convert_path_to_utf16(path, cifs_sb);
> if (utf16_path == NULL) {
> rc = -ENOMEM;
> goto notify_exit;
> --
> 2.20.1
>
--
Thanks,
Steve
prev parent reply other threads:[~2021-04-17 20:05 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-16 7:35 [PATCH] cifs: fix out-of-bound memory access when calling smb3_notify() at mount point Eugene Korenevsky
2021-04-17 20:05 ` Steve French [this message]
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