Commit f3947936 authored by Chen Gang's avatar Chen Gang Committed by David S. Miller

drivers/isdn: checkng length to be sure not memory overflow

sizeof (cmd.parm.cmsg.para) is 50 (MAX_CAPI_PARA_LEN).
  sizeof (cmd.parm) is 80+, but less than 100.
  strlen(msg) may be more than 80+ (Modem-Commandbuffer, less than 255).
    isdn_tty_send_msg is called by isdn_tty_parse_at
    the relative parameter is m->mdmcmd (atemu *m)
    the relative command may be "+M..."

  so need check the length to be sure not memory overflow.
    cmd.parm is a union, and need keep original valid buffer length no touch
Signed-off-by: default avatarChen Gang <>
Signed-off-by: default avatarDavid S. Miller <>
parent 2e85d676
...@@ -902,7 +902,9 @@ isdn_tty_send_msg(modem_info *info, atemu *m, char *msg) ...@@ -902,7 +902,9 @@ isdn_tty_send_msg(modem_info *info, atemu *m, char *msg)
int j; int j;
int l; int l;
l = strlen(msg); l = min(strlen(msg), sizeof(cmd.parm) - sizeof(cmd.parm.cmsg)
+ sizeof(cmd.parm.cmsg.para) - 2);
if (!l) { if (!l) {
isdn_tty_modem_result(RESULT_ERROR, info); isdn_tty_modem_result(RESULT_ERROR, info);
return; return;
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