This is a note to let you know that I've just added the patch titled cifs: fix regression when mounting shares with prefix paths to the 5.11-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: cifs-fix-regression-when-mounting-shares-with-prefix-paths.patch and it can be found in the queue-5.11 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 5c1acf3fe05ce443edba5e2110c9e581765f66a8 Mon Sep 17 00:00:00 2001 From: Paulo Alcantara <pc@xxxxxx> Date: Mon, 3 May 2021 11:55:26 -0300 Subject: cifs: fix regression when mounting shares with prefix paths From: Paulo Alcantara <pc@xxxxxx> commit 5c1acf3fe05ce443edba5e2110c9e581765f66a8 upstream. 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@xxxxxxxxxxxxxxx> # v5.11+ Fixes: 315db9a05b7a ("cifs: fix leak in cifs_smb3_do_mount() ctx") Signed-off-by: Paulo Alcantara (SUSE) <pc@xxxxxx> Acked-by: David Disseldorp <ddiss@xxxxxxx> Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/cifs/cifsfs.c | 8 +------- fs/cifs/connect.c | 24 ++++++++++++++++++------ fs/cifs/fs_context.c | 4 ++++ 3 files changed, 23 insertions(+), 13 deletions(-) --- a/fs/cifs/cifsfs.c +++ b/fs/cifs/cifsfs.c @@ -823,13 +823,7 @@ cifs_smb3_do_mount(struct file_system_ty 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); if (rc) { root = ERR_PTR(rc); goto out; --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -3150,17 +3150,29 @@ out: 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); + if (devname) { + cifs_dbg(FYI, "%s: devname=%s\n", __func__, devname); + 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; - cifs_dbg(FYI, "%s: mntopts=%s\n", __func__, mntopts); rc = smb3_parse_opt(mntopts, "ip", &ip); - if (!rc && !cifs_convert_address((struct sockaddr *)&ctx->dstaddr, ip, - strlen(ip))) { + if (rc) { + cifs_dbg(VFS, "%s: failed to parse ip options: %d\n", __func__, rc); + return rc; + } + + rc = cifs_convert_address((struct sockaddr *)&ctx->dstaddr, ip, strlen(ip)); + kfree(ip); + if (!rc) { cifs_dbg(VFS, "%s: failed to convert ip address\n", __func__); return -EINVAL; } @@ -3180,7 +3192,7 @@ cifs_setup_volume_info(struct smb3_fs_co return -EINVAL; } - return rc; + return 0; } static int --- a/fs/cifs/fs_context.c +++ b/fs/cifs/fs_context.c @@ -473,6 +473,7 @@ smb3_parse_devname(const char *devname, /* 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; @@ -483,6 +484,9 @@ smb3_parse_devname(const char *devname, if (*pos == '/' || *pos == '\\') pos++; + kfree(ctx->prepath); + ctx->prepath = NULL; + /* If pos is NULL then no prepath */ if (!*pos) return 0; Patches currently in stable-queue which might be from pc@xxxxxx are queue-5.11/cifs-fix-regression-when-mounting-shares-with-prefix-paths.patch queue-5.11/cifs-fix-leak-in-cifs_smb3_do_mount-ctx.patch