For example, when mount opt is redundently specified
(e.g., "user=A,user=B,user=C"), kernel kept allocating new key/val
with kstrdup() and overwrite previous ptr (to be freed).
Althouhg mkfs.cifs in userspace performs a bit of sanitization
(e.g., forcing one user option), current implementation is not
robust. Other options such as iocharset and domainanme are similary
vulnerable.
Signed-off-by: Taesoo Kim <tsgatesv@xxxxxxxxx>
---
fs/cifs/connect.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index d3aa999..4cb8450 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1599,6 +1599,8 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
pr_warn("CIFS: username too long\n");
goto cifs_parse_mount_err;
}
+
+ kfree(vol->username);
vol->username = kstrdup(string, GFP_KERNEL);
if (!vol->username)
goto cifs_parse_mount_err;
@@ -1700,6 +1702,7 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
goto cifs_parse_mount_err;
}
+ kfree(vol->domainname);
vol->domainname = kstrdup(string, GFP_KERNEL);
if (!vol->domainname) {
pr_warn("CIFS: no memory for domainname\n");
@@ -1731,6 +1734,7 @@ cifs_parse_mount_options(const char *mountdata, const char *devname,
}
if (strncasecmp(string, "default", 7) != 0) {
+ kfree(vol->iocharset);
vol->iocharset = kstrdup(string,
GFP_KERNEL);
if (!vol->iocharset) {
--
2.3.3
--
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