Re: [PATCH] cifs: fix automount regression of dfs links

FYI - Running the DFS tests now

http://smb3-test-rhel-75.southcentralus.cloudapp.azure.com/#/builders/3/buil...

On Fri, Apr 30, 2021 at 1:10 PM Paulo Alcantara pc@cjr.nz wrote:

Unfortunately we can't kfree() the UNC and prefix paths in cifs_smb3_do_mount() because they could have come from a chased DFS referral (automount) and we rely on the new values set in cifs_sb->ctx prior to calling cifs_mount().

Instead, fix smb3_parse_devname() to not leak the UNC and prefix paths when parsing new share 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 | 6 ------ fs/cifs/connect.c | 10 +++++++--- fs/cifs/fs_context.c | 2 ++ 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c index 8a6894577697..bfe98136f9c1 100644 --- a/fs/cifs/cifsfs.c +++ b/fs/cifs/cifsfs.c @@ -863,12 +863,6 @@ 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);
    if (rc) {
            root = ERR_PTR(rc);
  

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index becd5f807787..ee4a92cbcb29 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -3159,9 +3159,13 @@ static int do_dfs_failover(const char *path, const char *full_path, struct cifs_ int cifs_setup_volume_info(struct smb3_fs_context *ctx, const char *mntopts, const char *devname) {

•   int rc = 0;
  

•   int rc;
  
  

•   smb3_parse_devname(devname, ctx);
  

•   rc = smb3_parse_devname(devname, ctx);
  

•   if (rc) {
  

•           cifs_dbg(VFS, "%s: failed to parse %s: %d\n", __func__, devname, rc);
  

•           return rc;
  

•   }
  
    if (mntopts) {
            char *ip;
  

@@ -3189,7 +3193,7 @@ cifs_setup_volume_info(struct smb3_fs_context *ctx, const char *mntopts, const c return -EINVAL; }

•   return rc;
  

•   return 0;
  

}

static int diff --git a/fs/cifs/fs_context.c b/fs/cifs/fs_context.c index 1d6e0e15b034..b502a44e15a1 100644 --- a/fs/cifs/fs_context.c +++ b/fs/cifs/fs_context.c @@ -476,6 +476,7 @@ smb3_parse_devname(const char *devname, struct smb3_fs_context *ctx)

    /* move "pos" up to delimiter or NULL */
    pos += len;

•   kfree(ctx->UNC);
    ctx->UNC = kstrndup(devname, pos - devname, GFP_KERNEL);
    if (!ctx->UNC)
            return -ENOMEM;
  

@@ -490,6 +491,7 @@ smb3_parse_devname(const char *devname, struct smb3_fs_context *ctx) if (!*pos) return 0;

•   kfree(ctx->prepath);
    ctx->prepath = kstrdup(pos, GFP_KERNEL);
    if (!ctx->prepath)
            return -ENOMEM;
  

-- 2.31.1