From 340625e618e1b37a72a02f07aa7144ae0ab0b19e Mon Sep 17 00:00:00 2001 From: Ronnie Sahlberg Date: Tue, 27 Aug 2019 09:30:14 +1000 Subject: cifs: replace various strncpy with strscpy and similar Using strscpy is cleaner, and avoids some problems with handling maximum length strings. Linus noticed the original problem and Aurelien pointed out some additional problems. Fortunately most of this is SMB1 code (and in particular the ASCII string handling older, which is less common). Reported-by: Linus Torvalds Reviewed-by: Aurelien Aptel Signed-off-by: Ronnie Sahlberg Signed-off-by: Steve French --- fs/cifs/sess.c | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-) (limited to 'fs/cifs/sess.c') diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c index dcd49ad60c83..4c764ff7edd2 100644 --- a/fs/cifs/sess.c +++ b/fs/cifs/sess.c @@ -159,13 +159,16 @@ static void ascii_ssetup_strings(char **pbcc_area, struct cifs_ses *ses, const struct nls_table *nls_cp) { char *bcc_ptr = *pbcc_area; + int len; /* copy user */ /* BB what about null user mounts - check that we do this BB */ /* copy user */ if (ses->user_name != NULL) { - strncpy(bcc_ptr, ses->user_name, CIFS_MAX_USERNAME_LEN); - bcc_ptr += strnlen(ses->user_name, CIFS_MAX_USERNAME_LEN); + len = strscpy(bcc_ptr, ses->user_name, CIFS_MAX_USERNAME_LEN); + if (WARN_ON_ONCE(len < 0)) + len = CIFS_MAX_USERNAME_LEN - 1; + bcc_ptr += len; } /* else null user mount */ *bcc_ptr = 0; @@ -173,8 +176,10 @@ static void ascii_ssetup_strings(char **pbcc_area, struct cifs_ses *ses, /* copy domain */ if (ses->domainName != NULL) { - strncpy(bcc_ptr, ses->domainName, CIFS_MAX_DOMAINNAME_LEN); - bcc_ptr += strnlen(ses->domainName, CIFS_MAX_DOMAINNAME_LEN); + len = strscpy(bcc_ptr, ses->domainName, CIFS_MAX_DOMAINNAME_LEN); + if (WARN_ON_ONCE(len < 0)) + len = CIFS_MAX_DOMAINNAME_LEN - 1; + bcc_ptr += len; } /* else we will send a null domain name so the server will default to its own domain */ *bcc_ptr = 0; @@ -242,9 +247,10 @@ static void decode_ascii_ssetup(char **pbcc_area, __u16 bleft, kfree(ses->serverOS); - ses->serverOS = kzalloc(len + 1, GFP_KERNEL); + ses->serverOS = kmalloc(len + 1, GFP_KERNEL); if (ses->serverOS) { - strncpy(ses->serverOS, bcc_ptr, len); + memcpy(ses->serverOS, bcc_ptr, len); + ses->serverOS[len] = 0; if (strncmp(ses->serverOS, "OS/2", 4) == 0) cifs_dbg(FYI, "OS/2 server\n"); } @@ -258,9 +264,11 @@ static void decode_ascii_ssetup(char **pbcc_area, __u16 bleft, kfree(ses->serverNOS); - ses->serverNOS = kzalloc(len + 1, GFP_KERNEL); - if (ses->serverNOS) - strncpy(ses->serverNOS, bcc_ptr, len); + ses->serverNOS = kmalloc(len + 1, GFP_KERNEL); + if (ses->serverNOS) { + memcpy(ses->serverNOS, bcc_ptr, len); + ses->serverNOS[len] = 0; + } bcc_ptr += len + 1; bleft -= len + 1; -- cgit v1.2.3