From d2635457d4263f6b9cb87088aa8a1799a6f23424 Mon Sep 17 00:00:00 2001 From: Len Baker Date: Tue, 17 Aug 2021 12:27:09 +0200 Subject: [PATCH] CIFS: Fix a potencially linear read overflow [ Upstream commit f980d055a0f858d73d9467bb0b570721bbfcdfb8 ] strlcpy() reads the entire source buffer first. This read may exceed the destination size limit. This is both inefficient and can lead to linear read overflows if a source string is not NUL-terminated. Also, the strnlen() call does not avoid the read overflow in the strlcpy function when a not NUL-terminated string is passed. So, replace this block by a call to kstrndup() that avoids this type of overflow and does the same. Fixes: 066ce6899484d ("cifs: rename cifs_strlcpy_to_host and make it use new functions") Signed-off-by: Len Baker Reviewed-by: Paulo Alcantara (SUSE) Reviewed-by: Jeff Layton Signed-off-by: Steve French Signed-off-by: Sasha Levin --- fs/cifs/cifs_unicode.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/fs/cifs/cifs_unicode.c b/fs/cifs/cifs_unicode.c index 9bd03a231032..171ad8b42107 100644 --- a/fs/cifs/cifs_unicode.c +++ b/fs/cifs/cifs_unicode.c @@ -358,14 +358,9 @@ cifs_strndup_from_utf16(const char *src, const int maxlen, if (!dst) return NULL; cifs_from_utf16(dst, (__le16 *) src, len, maxlen, codepage, - NO_MAP_UNI_RSVD); + NO_MAP_UNI_RSVD); } else { - len = strnlen(src, maxlen); - len++; - dst = kmalloc(len, GFP_KERNEL); - if (!dst) - return NULL; - strlcpy(dst, src, len); + dst = kstrndup(src, maxlen, GFP_KERNEL); } return dst;