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cifs: fix regression when mounting shares with prefix paths 

The commit 315db9a05b ("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: 315db9a05b ("cifs: fix leak in cifs_smb3_do_mount() ctx")
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Acked-by: David Disseldorp <ddiss@suse.de>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Paulo Alcantara 2021-05-03 11:55:26 -03:00 committed by Steve French
parent 5b2abdafbe
commit 5c1acf3fe0
3 changed files with 23 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
fs/cifs/cifsfs.c
View File

@ -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;

24
fs/cifs/connect.c
View File

@ -3149,17 +3149,29 @@ 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;
}
@ -3179,7 +3191,7 @@ cifs_setup_volume_info(struct smb3_fs_context *ctx, const char *mntopts, const c
return -EINVAL;
}
return rc;
return 0;
}
static int

4
fs/cifs/fs_context.c
View File

@ -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;