[Dovecot] Mails causing imap process to hang.

Tan Shao Yi tansy at pacific.net.sg
Thu Aug 9 10:55:00 EEST 2007


Hi Timo,

We are getting e-mails from a certain domain that seem to cause the IMAP 
process to hang.

Here's how it looks like if we issued a FETCH 40 FULL:

* 40 FETCH (FLAGS (\Seen) INTERNALDATE "09-Aug-2007 11:50:44 +0800" 
RFC822.SIZE 803392
  ENVELOPE ("Thu, 09 Aug 2007 11:09:09 +0800 (CST)" {64}
8¤ë¸¹Âø»x¤C¤Ñ¤W¬[79§é !! SmartÀ°±zÄY¿ï¥|¤j°Ï°ì20Àɳ̷í¼ö°òª÷±ÀÂË 
(("=?Big5?B?s9WryKjTpKSk5cL4u3ikS6TruLk=?=" NIL "mailsender" "books.com.tw")) 
(("=?Big5?B?s9WryKjTpKSk5cL4u3ikS6TruLk=?=" NIL "mailsender" "books.com.tw")) 
(("=?Big5?B?s9WryKjTuvS49K7RqbE=?=" NIL "mailsender" "books.com.tw")) NIL NIL NIL NIL 
"<20070809035039.JDYJ10720.mta2.pacific.net.sg at mx3.pacific.net.sg>") BODY ("text" 
"html" ("charset" "Big5") NIL NIL "base64" 801726 10279))

A truss of the process reveals:

write(1, " *   4 0   F E T C H   (".., 36)      = 36
sendfilev64(1, 1, 0xFFBFF2C0, 1, 0xFFBFF2B4)    = 65536
close(10)                                       = 0
close(8)                                        = 0
open64("/var/qmail/maildirs/09/44/XXXXXX/Maildir/maildirsize", 
O_RDWR|O_APPEND) = 8
read(8, " 1 0 4 8 5 7 6 0 S\n 6 4".., 5120)     = 1188
read(8, 0xFFBFE3FC, 3932)                       = 0
write(1, " )\r\n 0 0 0 0 0 0 1 0  ".., 33)      = 33
pollsys(0x000B0378, 3, 0xFFBFF888, 0x00000000)  = 1
read(0, " 0 0 0 0 0 0 1 1   F E T".., 2769)     = 42
close(8)                                        = 0
open64("/var/qmail/maildirs/09/44/XXXXXX/Maildir/maildirsize", 
O_RDWR|O_APPEND) = 8
read(8, " 1 0 4 8 5 7 6 0 S\n 6 4".., 5120)     = 1188
read(8, 0xFFBFE4FC, 3932)                       = 0
open64("/var/qmail/maildirs/09/44/XXXXXX/Maildir/cur/1186631443.M495843P21207V000000940000BF68I000000000030AFC0_0.recess4,S=803364:2,S", 
O_RDONLY) = 10
fstat64(10, 0xFFBFF2A0)                         = 0
pread64(10, " A g I C A 8 d G Q g Y 2".., 4096, 58982) = 4096
pread64(10, " R p b m c 9 I j A i P g".., 4096, 63078) = 4096
pread64(10, " O V 8 w M D F f M D M y".., 4096, 67174) = 4096
pread64(10, " Z W M v Y X M v M j A w".., 4096, 71270) = 4096
pread64(10, " 4 K I C A g I C A g I C".., 4096, 75366) = 4096
pread64(10, " A g I C A g I C A g I C".., 4096, 79462) = 4096
pread64(10, " I C A g I C A 8 L 3 R y".., 4096, 83558) = 4096
pread64(10, " c y 5 j b 2 0 u d H c v".., 4096, 87654) = 4096
pread64(10, " A g I C A g I C A g I C".., 4096, 91750) = 4096
pread64(10, " A 4 N j A i P j x p b W".., 4096, 95846) = 4096
pread64(10, " I C A 8 d G Q + I A o g".., 4096, 99942) = 4096
pread64(10, " U j A z L z k v U j A z".., 4096, 104038) = 4096
pread64(10, " A g P H R k I G N v b H".., 4096, 108134) = 4096
pread64(10, " R k P g o g I C A g\r\n".., 4096, 112230) = 4096
pread64(10, " I C A g I C A g I D x 0".., 4096, 116326) = 4096
pread64(10, " e m l u Z S 9 t\r\n Y W".., 4096, 120422) = 4096
pread64(10, " J 0 Z X h 0 I j 6 q s a".., 4096, 124518) = 4096
fstat64(10, 0x000D6610)                         = 0
write(1, " *   4 0   F E T C H   (".., 38)      = 38
sendfilev64(1, 1, 0xFFBFF2C0, 1, 0xFFBFF2B4)    = 131072
close(10)                                       = 0
close(8)                                        = 0
open64("/var/qmail/maildirs/09/44/XXXXXX/Maildir/maildirsize", 
O_RDWR|O_APPEND) = 8
read(8, " 1 0 4 8 5 7 6 0 S\n 6 4".., 5120)     = 1188
read(8, 0xFFBFE3FC, 3932)                       = 0
write(1, " )\r\n 0 0 0 0 0 0 1 1  ".., 33)      Err#11 EAGAIN
pollsys(0x000B0378, 4, 0xFFBFF888, 0x00000000)  = 1
write(1, " )\r\n 0 0 0 0 0 0 1 1  ".., 33)      = 33
pollsys(0x000B0378, 3, 0xFFBFF888, 0x00000000)  = 1
read(0, " 0 0 0 0 0 0 1 2   F E T".., 2727)     = 42
close(8)                                        = 0
open64("/var/qmail/maildirs/09/44/XXXXXX/Maildir/maildirsize", 
O_RDWR|O_APPEND) = 8
read(8, " 1 0 4 8 5 7 6 0 S\n 6 4".., 5120)     = 1188
read(8, 0xFFBFE4FC, 3932)                       = 0
open64("/var/qmail/maildirs/09/44/XXXXXX/Maildir/cur/1186631443.M495843P21207V000000940000BF68I000000000030AFC0_0.recess4,S=803364:2,S", 
O_RDONLY) = 10
fstat64(10, 0xFFBFF2A0)                         = 0
pread64(10, " J 0 Z X h 0 I j 6 q s a".., 4096, 124518) = 4096
pread64(10, " c v Z X h l\r\n Y y 9 h".., 4096, 128614) = 4096
pread64(10, " I C A g I C A g I C A g".., 4096, 132710) = 4096
pread64(10, " I C A g\r\n I C A g C i".., 4096, 136806) = 4096
pread64(10, " A g I C A g I C A g I C".., 4096, 140902) = 4096
pread64(10, " w v\r\n d H I + C i A g".., 4096, 144998) = 4096
pread64(10, " Z H R o P S I 4 M S I g".., 4096, 149094) = 4096
pread64(10, "\r\n b 2 x z c G F u P S".., 4096, 153190) = 4096
pread64(10, " T r u L k v M j A w N y".., 4096, 157286) = 4096
pread64(10, " c j 4 K I C A g I C A g".., 4096, 161382) = 4096
pread64(10, " I C A g P H R k I G N v".., 4096, 165478) = 4096
pread64(10, " E g a H J l Z j 0 i a H".., 4096, 169574) = 4096
pread64(10, " A g I C A g I C A 8 d H".., 4096, 173670) = 4096
pread64(10, " I i B o Z W l n a H Q 9".., 4096, 177766) = 4096
pread64(10, " I D x 0 Z C B j b 2 x z".., 4096, 181862) = 4096
pread64(10, " M u Z 2 l m I i B 3 a W".., 4096, 185958) = 4096
pread64(10, " l 3 u / m h R z x z P j".., 4096, 190054) = 4096
pread64(10, " I C A g I C A 8 L 3 R y".., 4096, 194150) = 4096
pread64(10, " Y 2 9 t L n R 3 L 0 c v".., 4096, 198246) = 4096
pread64(10, " R k P g o g I C A g I C".., 4096, 202342) = 4096
pread64(10, " A g P H R y P i A K I C".., 4096, 206438) = 4096
pread64(10, " I C A g I C A g I C A g".., 4096, 210534) = 4096
pread64(10, " Z W 0 9 U j A z M D A w".., 4096, 214630) = 4096
pread64(10, " M v Y X M v M j A w N z".., 4096, 218726) = 4096
pread64(10, " A g I C A g I C A g P H".., 4096, 222822) = 4096
pread64(10, " P H R k I G N v b H N w".., 4096, 226918) = 4096
pread64(10, " I C A g I C A g I C A g".., 4096, 231014) = 4096
pread64(10, " I + C i A g I C A g I C".., 4096, 235110) = 4096
pread64(10, " A g I C A g I C A g I C".., 4096, 239206) = 4096
pread64(10, " I D x 0 Z D 4 8 L 3 R k".., 4096, 243302) = 4096
pread64(10, " I C A g I C A g I D x 0".., 4096, 247398) = 4096
pread64(10, " A g I C A g I C A g I C".., 4096, 251494) = 4096
pread64(10, " R 0 c D o v L 2 F k Z G".., 4096, 255590) = 4096
fstat64(10, 0x000CB208)                         = 0
write(1, " *   4 0   F E T C H   (".., 38)      = 38
sendfilev64(1, 1, 0xFFBFF2C0, 1, 0xFFBFF2B4)    Err#11 EAGAIN
fstat64(10, 0x000CB208)                         = 0
sendfilev64(1, 1, 0xFFBFF4A0, 1, 0xFFBFF494)    Err#11 EAGAIN
pollsys(0x000B0378, 4, 0xFFBFF888, 0x00000000)  = 1
fstat64(10, 0x000CB208)                         = 0
sendfilev64(1, 1, 0xFFBFF4A0, 1, 0xFFBFF494)    Err#11 EAGAIN
pollsys(0x000B0378, 4, 0xFFBFF888, 0x00000000)  = 1
fstat64(10, 0x000CB208)                         = 0
sendfilev64(1, 1, 0xFFBFF4A0, 1, 0xFFBFF494)    Err#11 EAGAIN
pollsys(0x000B0378, 4, 0xFFBFF888, 0x00000000)  = 1
fstat64(10, 0x000CB208)                         = 0
sendfilev64(1, 1, 0xFFBFF4A0, 1, 0xFFBFF494)    Err#11 EAGAIN
pollsys(0x000B0378, 4, 0xFFBFF888, 0x00000000)  = 1
fstat64(10, 0x000CB208)                         = 0
sendfilev64(1, 1, 0xFFBFF4A0, 1, 0xFFBFF494)    Err#11 EAGAIN


This goes on and on... consuming all bandwidth on the system.

Is there something wrong with this particular e-mail? I will be attaching 
it in a separate e-mail to you to protect the user's privacy.

Thanking in advance.

Cheers,
Tan Shao Yi


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