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); if (rc) { root = ERR_PTR(rc); goto out; diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index becd5f807787..4ce6fc24cae1 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -3159,17 +3159,29 @@ 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); + 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; } @@ -3189,7 +3201,7 @@ 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..3bcf881c3ae9 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; @@ -486,6 +487,9 @@ smb3_parse_devname(const char *devname, struct smb3_fs_context *ctx) if (*pos == '/' || *pos == '\') pos++;
+ kfree(ctx->prepath); + ctx->prepath = NULL; + /* If pos is NULL then no prepath */ if (!*pos) return 0;