added acked-by and merged into cifs-2.6.git for-next
On Mon, May 3, 2021 at 6:20 PM David Disseldorp ddiss@suse.de wrote:
On Mon, 3 May 2021 11:55:26 -0300, Paulo Alcantara wrote:
The commit 315db9a05b7a ("cifs: fix leak in cifs_smb3_do_mount() ctx") revealed an existing bug when mounting shares that contain a prefix path or DFS links.
cifs_setup_volume_info() requires the @devname to contain the full path (UNC + prefix) to update the fs context with the new UNC and prepath values, however we were passing only the UNC path (old_ctx->UNC) in @device thus discarding any prefix paths.
Instead of concatenating both old_ctx->{UNC,prepath} and pass it in @devname, just keep the dup'ed values of UNC and prepath in cifs_sb->ctx after calling smb3_fs_context_dup(), and fix smb3_parse_devname() to correctly parse and not leak the new UNC and prefix paths.
Cc: stable@vger.kernel.org # v5.11+ Fixes: 315db9a05b7a ("cifs: fix leak in cifs_smb3_do_mount() ctx") Signed-off-by: Paulo Alcantara (SUSE) pc@cjr.nz
fs/cifs/cifsfs.c | 8 +------- fs/cifs/connect.c | 24 ++++++++++++++++++------ fs/cifs/fs_context.c | 4 ++++ 3 files changed, 23 insertions(+), 13 deletions(-)
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c index 8a6894577697..d7ea9c5fe0f8 100644 --- a/fs/cifs/cifsfs.c +++ b/fs/cifs/cifsfs.c @@ -863,13 +863,7 @@ cifs_smb3_do_mount(struct file_system_type *fs_type, goto out; }
/* cifs_setup_volume_info->smb3_parse_devname() redups UNC & prepath */kfree(cifs_sb->ctx->UNC);cifs_sb->ctx->UNC = NULL;kfree(cifs_sb->ctx->prepath);cifs_sb->ctx->prepath = NULL;rc = cifs_setup_volume_info(cifs_sb->ctx, NULL, old_ctx->UNC);
rc = cifs_setup_volume_info(cifs_sb->ctx, NULL, NULL);IIUC, with the new behaviour, this call becomes pretty much an if (!cifs_sb->ctx->username) root = ERR_PTR(-EINVAL);
So it might be worth simplifying this further. Either way: Acked-by: David Disseldorp ddiss@suse.de
Cheers, David