Package: libgdbm3
Version: 1.8.3-3
Severity: important
An application can enter on an infinite loop when reading data.
This occour at random times.
I already traced the error and find that the problem is with the patch
05_handle-short-read.dpatch introduced at bug #274417.
This patch makes it possible that libgdbm3 keep trying to read the file even
if the EOF is returned.
** From the patch:
****************************
@@ -111,7 +112,12 @@
if (file_pos != bucket_adr)
_gdbm_fatal (dbf, "lseek error");
- num_bytes = read (dbf->desc, dbf->bucket, dbf->header->bucket_size);
+ do
+ {
+ bytes_read = read (dbf->desc, dbf->bucket+num_bytes,
dbf->header->bucket_size-num_bytes);
+ num_bytes += bytes_read;
+ }
+ while ((bytes_read > 0 || errno == EINTR) && num_bytes <
dbf->header->bucket_size);
if (num_bytes != dbf->header->bucket_size)
_gdbm_fatal (dbf, "read error");
}
****************************
As could be seen the "while ((bytes_read > 0 || errno == EINTR) && num_bytes <
dbf->header->bucket_size);" if the read return EINTR then bytes_read will be 0
and if num_byes still less then bucket_size the application will be locked
on the loop.
I have strace some process during the lock. It took me more then a year to find
that.
My application stop on several different severs at random times. Some times
once a week, but it happens to be more then once a day too.
After I removed this patch and rebuild libgdgm3 I had never had a hang
again. It has about 1 month I did that.
1) strace during normal operation
(file descriptor 4 is a gdbm file)
------------------------------------------------
17:46:05.482106 rt_sigaction(SIGCHLD, {SIG_DFL}, {0x404ae0, [CHLD],
SA_RESTORER|SA_RESTART, 0x7f4144f8af60}, 8) = 0
17:46:05.482278 rt_sigprocmask(SIG_UNBLOCK, [CHLD], NULL, 8) = 0
17:46:05.482683 brk(0x2503000) = 0x2503000
17:46:05.482974 brk(0x2524000) = 0x2524000
17:46:05.483454 brk(0x2545000) = 0x2545000
17:46:05.483729 lseek(4, 8192, SEEK_SET) = 8192
17:46:05.484210 read(4, "\0\0\0\0\r\0\0\0\31\0\0\0\271\3627
216.\2474\0\0\0\0\0\0\16\0\0\0\31"..., 4096) = 4096
17:46:05.484686 getsockname(5, {sa_family=AF_INET6, sin6_port=htons(25),
inet_pton(AF_INET6, "::ffff:74.86.76.42", &sin6_addr), sin6_flowinfo=0,
sin6_scope_id=0}, [28]) = 0
17:46:05.485206 open("/etc/resolv.conf", O_RDONLY) = 6
.
.
. normal process end..
---------------------------------------------
2) strace when the application starts degradating performance
----------------------------------------------
17:46:43.742191 rt_sigaction(SIGCHLD, {SIG_DFL}, {0x404ae0, [CHLD],
SA_RESTORER|SA_RESTART, 0x7f4144f8af60}, 8) = 0
17:46:43.743147 rt_sigprocmask(SIG_UNBLOCK, [CHLD], NULL, 8) = 0
17:46:43.748307 brk(0x2503000) = 0x2503000
17:46:43.753416 brk(0x2524000) = 0x2524000
17:46:43.753745 brk(0x2545000) = 0x2545000
17:46:43.754507 lseek(4, 8192, SEEK_SET) = 8192
17:46:43.754836 read(4, "201.17.129.83allow,SIZELIMIT=5242"..., 4096) = 1650
17:46:43.755069 read(4, ""..., 2446) = 0
17:46:43.756458 read(4, ""..., 2446) = 0
17:46:43.756556 read(4, ""..., 2446) = 0
17:46:43.756994 read(4, ""..., 2446) = 0
17:46:43.757080 read(4, ""..., 2446) = 0
17:46:43.757188 read(4, ""..., 2446) = 0
17:46:43.757276 read(4, ""..., 2446) = 0
17:46:43.757367 read(4, ""..., 2446) = 0
17:46:43.757452 read(4, ""..., 2446) = 0
17:46:43.757534 read(4, ""..., 2446) = 0
17:46:43.757617 read(4, ""..., 2446) = 0
17:46:43.757703 read(4, ""..., 2446) = 0
17:46:43.757794 read(4, ""..., 2446) = 0
17:46:43.757877 read(4, ""..., 2446) = 0
17:46:43.757960 read(4, ""..., 2446) = 0
17:46:43.758047 read(4, ""..., 2446) = 0
17:46:43.758155 read(4, ""..., 2446) = 0
17:46:43.758260 read(4, ""..., 2446) = 0
17:46:43.758570 read(4, ""..., 2446) = 0
17:46:43.758654 read(4, ""..., 2446) = 0
17:46:43.758762 read(4,
"\1\0\0\0\0\0\0\0\216\t\0\0\0\0\0\0r6\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"...,
2446) = 2446
17:46:43.759082 getsockname(5, {sa_family=AF_INET6, sin6_port=htons(25),
inet_pton(AF_INET6, "::ffff:74.86.76.42", &sin6_addr), sin6_flowinfo=0,
sin6_scope_id=0}, [28]) = 0
17:46:43.759258 open("/etc/resolv.conf", O_RDONLY) = 6
.
.
.
. normal process end..
----------------------------------------------
3) strace during a complete hang
---------------------------------------------
17:46:49.944384 rt_sigaction(SIGCHLD, {SIG_DFL}, {0x404ae0, [CHLD],
SA_RESTORER|SA_RESTART, 0x7f4144f8af60}, 8) = 0
17:46:49.950918 rt_sigprocmask(SIG_UNBLOCK, [CHLD], NULL, 8) = 0
17:46:49.951420 brk(0x2503000) = 0x2503000
17:48:05.794865 brk(0x2524000) = 0x2524000
17:48:05.795256 brk(0x2545000) = 0x2545000
17:48:45.322594 lseek(4, 8192, SEEK_SET) = 8192
17:48:45.322770 read(4, "201.17.129.83allow,SIZELIMIT=5242"..., 4096) = 1650
17:48:45.322967 read(4, ""..., 2446) = 0
17:48:45.323220 read(4, ""..., 2446) = 0
17:48:45.323390 read(4, ""..., 2446) = 0
17:48:45.323529 read(4, ""..., 2446) = 0
17:48:45.323675 read(4, ""..., 2446) = 0
17:48:45.323812 read(4, ""..., 2446) = 0
17:48:45.323937 read(4, ""..., 2446) = 0
17:48:45.324074 read(4, ""..., 2446) = 0
17:48:45.324215 read(4, ""..., 2446) = 0
17:48:45.324377 read(4, ""..., 2446) = 0
.
.
. until I kill the proccess
---------------------------------------------
I dont know why the read seems to be starting on the middle of the file, not
on the start. May be its related to the short read bug. My file is
located on a local ext3 hard disk. Anyway libgdbm cant go on a infinite loop
like that.
Marcus Pereira
-- System Information:
Debian Release: lenny/sid
APT prefers stable
APT policy: (500, 'stable')
Architecture: i386 (i686)
Shell: /bin/sh linked to /bin/bash
Kernel: Linux 2.6.18-6-686
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Versions of packages libgdbm3 depends on:
ii libc6 2.7-13 GNU C Library: Shared libraries
libgdbm3 recommends no packages.
-- no debconf information
--
To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org
with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
