1 2 3 K N O W N B U G S I N S E N D M A I L 4 5 6The following are bugs or deficiencies in sendmail that I am aware of 7but which have not been fixed in the current release. You probably 8want to get the most up to date version of this from ftp.sendmail.org 9in /pub/sendmail/KNOWNBUGS. For descriptions of bugs that have been 10fixed, see the file RELEASE_NOTES (in the root directory of the sendmail 11distribution). 12 13This list is not guaranteed to be complete. 14 15* Delivery to programs that generate too much output may cause problems 16 (8.10, 8.11) 17 18 If e-mail is delivered to a program which generates too much 19 output, then sendmail may issue an error: 20 21 timeout waiting for input from local during Draining Input 22 23 Make sure that the program does not generate output beyond a 24 status message (corresponding to the exit status). This may 25 require a wrapper around the actual program to redirect output 26 to /dev/null. 27 28 Such a problem has been reported for bulk_mailer. 29 30* Null bytes are not handled properly in headers. 31 32 Sendmail should handle full binary data. As it stands, it handles 33 all values in the body, but only 0x01-0x80 and 0xA0-0xFF in 34 the header. Notably missing is 0x00, which would require a major 35 restructuring of the code -- for example, almost no C library support 36 could be used to handle strings. 37 38* Duplicate error messages. 39 40 Sometimes identical, duplicate error messages can be generated. As 41 near as I can tell, this is rare and relatively innocuous. 42 43* $c (hop count) macro improperly set. 44 45 The $c macro is supposed to contain the current hop count, for use 46 when calling a mailer. This macro is initialized too early, and 47 is always zero (or the value of the -c command line flag, if any). 48 This macro will probably be removed entirely in a future release; 49 I don't believe there are any mailers left that require it. 50 51* \231 considered harmful. 52 53 Header addresses that have the \231 character (and possibly others 54 in the range \201 - \237) behave in odd and usually unexpected ways. 55 56* accept() problem on SVR4. 57 58 Apparently, the sendmail daemon loop (doing accept()s on the network) 59 can get into a weird state on SVR4; it starts logging ``SYSERR: 60 getrequests: accept: Protocol Error''. The workaround is to kill 61 and restart the sendmail daemon. We don't have an SVR4 system at 62 Berkeley that carries more than token mail load, so I can't validate 63 this. It is likely to be a glitch in the sockets emulation, since 64 "Protocol Error" is not possible error code with Berkeley TCP/IP. 65 66 I've also had someone report the message ``sendmail: accept: 67 SIOCGPGRP failed errno 22'' on an SVR4 system. This message is 68 not in the sendmail source code, so I assume it is also a bug 69 in the sockets emulation. (Errno 22 is EINVAL "Invalid Argument" 70 on all the systems I have available, including Solaris 2.x.) 71 Apparently, this problem is due to linking -lc before -lsocket; 72 if you are having this problem, check your Makefile. 73 74* accept() problem on Linux. 75 76 The accept() in sendmail daemon loop can return ETIMEDOUT. An 77 error is reported to syslog: 78 79 Jun 9 17:14:12 hostname sendmail[207]: NOQUEUE: SYSERR(root): 80 getrequests: accept: Connection timed out 81 82 "Connection timed out" is not documented as a valid return from 83 accept(2) and this was believed to be a bug in the Linux kernel. 84 Later information from the Linux kernel group states that Linux 85 2.0 kernels follow RFC1122 while sendmail follows the original BSD 86 (now POSIX 1003.1g draft) specification. The 2.1.X and later kernels 87 will follow the POSIX draft. 88 89* Excessive mailing list nesting can run out of file descriptors. 90 91 If you have a mailing list that includes lots of other mailing 92 lists, each of which has a separate owner, you can run out of 93 file descriptors. Each mailing list with a separate owner uses 94 one open file descriptor (prior to 8.6.6 it was three open 95 file descriptors per list). This is particularly egregious if 96 you have your connection cache set to be large. 97 98* Connection caching breaks if you pass the port number as an argument. 99 100 If you have a definition such as: 101 102 Mport, P=[IPC], F=kmDFMuX, S=11/31, R=21, 103 M=2100000, T=DNS/RFC822/SMTP, 104 A=IPC [127.0.0.1] $h 105 106 (i.e., where $h is the port number instead of the host name) the 107 connection caching code will break because it won't notice that 108 two messages addressed to different ports should use different 109 connections. 110 111* ESMTP SIZE underestimates the size of a message 112 113 Sendmail makes no allowance for headers that it adds, nor does it 114 account for the SMTP on-the-wire \r\n expansion. It probably doesn't 115 allow for 8->7 bit MIME conversions either. 116 117* Paths to programs being executed and the mode of program files are 118 not checked. Essentially, the RunProgramInUnsafeDirPath and 119 RunWritableProgram bits in the DontBlameSendmail option are always 120 set. This is not a problem if your system is well managed (that is, 121 if binaries and system directories are mode 755 instead of something 122 foolish like 777). 123 124* 8-bit data in GECOS field 125 126 If the GECOS (personal name) information in the passwd file contains 127 8-bit characters, those characters can be included in the message 128 header, which can cause problems when sending SMTP to hosts that 129 only accept 7-bit characters. 130 131* 8->7 bit MIME conversion 132 133 When sendmail is doing 8->7 bit MIME conversions, and the message 134 contains certain MIME body types that cannot be converted to 7-bit, 135 sendmail will strip the message to 7-bit. 136 137* 7->8 bit MIME conversion 138 139 If a message that is encoded as 7-bit MIME is converted to 8-bit and 140 that message when decoded is illegal (e.g., because of long lines or 141 illegal characters), sendmail can produce an illegal message. 142 143* MIME encoded full name phrases in the From: header 144 145 If a full name phrase includes characters from MustQuoteChars, sendmail 146 will quote the entire full name phrase. If MustQuoteChars includes 147 characters which are not special characters according to STD 11 (RFC 148 822), this quotation can interfere with MIME encoded full name phrases. 149 By default, sendmail includes the single quote character (') in 150 MustQuoteChars even though it is not listed as a special character in 151 STD 11. 152 153* bestmx map with -z flag truncates the list of MX hosts 154 155 A bestmx map configured with the -z flag will truncate the list 156 of MX hosts. This prevents creation of strings which are too 157 long for ruleset parsing. This can have an adverse effect on the 158 relay_based_on_MX feature. 159 160* Saving to ~sender/dead.letter fails if su'ed to root 161 162 If ErrorMode is set to print and an error in sending mail occurs, 163 the normal action is to print a message to the screen and append 164 the message to a dead.letter file in the sender's home directory. 165 In the case where the sender is using su to act as root, the file 166 safety checks prevent sendmail from saving the dead.letter file 167 because the sender's uid and the current real uid do not match. 168 169* Berkeley DB 2.X race condition with fcntl() locking 170 171 There is a race condition for Berkeley DB 2.X databases on 172 operating systems which use fcntl() style locking, such as 173 Solaris. Sendmail locks the map before calling db_open() to 174 prevent others from modifying the map while it is being opened. 175 Unfortunately, Berkeley DB opens the map, closes it, and then 176 reopens it. fcntl() locking drops the lock when any file 177 descriptor pointing to the file is closed, even if it is a 178 different file descriptor than the one used to initially lock 179 the file. As a result there is a possibility that entries in a 180 map might not be found during a map rebuild. As a workaround, 181 you can use makemap to build a map with a new name and then 182 "mv" the new db file to replace the old one. 183 184 Sleepycat Software has added code to avoid this race condition to 185 Berkeley DB versions after 2.7.5. 186 187* File open timeouts not available on hard mounted NFS file systems 188 189 Since SIGALRM does not interrupt an RPC call for hard mounted 190 NFS file systems, it is impossible to implement a timeout on a file 191 open operation. Therefore, while the NFS server is not responding, 192 attempts to open a file on that server will hang. Systems with 193 local mail delivery and NFS hard mounted home directories should be 194 avoided, as attempts to open the forward files could hang. 195 196* Race condition for delivery to setuid files 197 198 Sendmail will deliver to a fail if the file is owned by the DefaultUser 199 or has the setuid bit set. Unfortunately, some systems clear that bit 200 when a file is modified. Sendmail compensates by resetting the file mode 201 back to it's original settings. Unfortunately, there's still a 202 permission failure race as sendmail checks the permissions before locking 203 the file. This is unavoidable as sendmail must verify the file is safe 204 to open before opening it. A file can not be locked until it is open. 205 206* Potential denial of service attack with AutoRebuildAliases 207 208 There is a potential for a denial of service attack if the 209 AutoRebuildAliases option is set as a user can kill the sendmail process 210 while it is rebuilding the aliases file leaving it in an inconsistent 211 state. This option and it's use is deprecated and will be removed from a 212 future version of sendmail. 213 214$Revision: 8.43.16.1 $, Last updated $Date: 2000/09/28 00:45:37 $ 215