From: Thiago Rafael Becker <trbecker@gmail.com> mainline inclusion from mainline-v5.16-rc6 commit a31080899d5fdafcccf7f39dd214a814a2c82626 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6D6RL CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- mount.cifs can pass a device with multiple delimiters in it. This will cause rename(2) to fail with ENOENT. V2: - Make sanitize_path more readable. - Fix multiple delimiters between UNC and prepath. - Avoid a memory leak if a bad user starts putting a lot of delimiters in the path on purpose. BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=2031200 Fixes: 24e0a1eff9e2 ("cifs: switch to new mount api") Cc: stable@vger.kernel.org # 5.11+ Acked-by: Ronnie Sahlberg <lsahlber@redhat.com> Signed-off-by: Thiago Rafael Becker <trbecker@gmail.com> Signed-off-by: Steve French <stfrench@microsoft.com> conflicts: fs/cifs/fs_context.c Signed-off-by: ZhaoLong Wang <wangzhaolong1@huawei.com> Reviewed-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com> Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com> --- fs/cifs/connect.c | 38 +++++++++++++++++++++++++++++++++++++- 1 file changed, 37 insertions(+), 1 deletion(-) diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index 7f5d173760cf..0a2eced46e35 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -1316,6 +1316,42 @@ static int get_option_gid(substring_t args[], kgid_t *result) return 0; } +/* + * Remove duplicate path delimiters. Windows is supposed to do that + * but there are some bugs that prevent rename from working if there are + * multiple delimiters. + * + * Returns a sanitized duplicate of @path. The caller is responsible for + * cleaning up the original. + */ +#define IS_DELIM(c) ((c) == '/' || (c) == '\\') +static char *sanitize_path(char *path) +{ + char *cursor1 = path, *cursor2 = path; + + /* skip all prepended delimiters */ + while (IS_DELIM(*cursor1)) + cursor1++; + + /* copy the first letter */ + *cursor2 = *cursor1; + + /* copy the remainder... */ + while (*(cursor1++)) { + /* ... skipping all duplicated delimiters */ + if (IS_DELIM(*cursor1) && IS_DELIM(*cursor2)) + continue; + *(++cursor2) = *cursor1; + } + + /* if the last character is a delimiter, skip it */ + if (IS_DELIM(*(cursor2 - 1))) + cursor2--; + + *(cursor2) = '\0'; + return kstrdup(path, GFP_KERNEL); +} + /* * Parse a devname into substrings and populate the vol->UNC and vol->prepath * fields with the result. Returns 0 on success and an error otherwise. @@ -1364,7 +1400,7 @@ cifs_parse_devname(const char *devname, struct smb_vol *vol) if (!*pos) return 0; - vol->prepath = kstrdup(pos, GFP_KERNEL); + vol->prepath = sanitize_path(pos); if (!vol->prepath) return -ENOMEM; -- 2.25.1