Bug 453086

Summary: dmesg(8) memory leak
Product: Red Hat Enterprise Linux 5 Reporter: masanari iida <masanari_iida>
Component: util-linuxAssignee: Karel Zak <kzak>
Status: CLOSED WONTFIX QA Contact: Ben Levenson <benl>
Severity: low Docs Contact:
Priority: low    
Version: 5.1   
Target Milestone: rc   
Target Release: ---   
Hardware: i386   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
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Story Points: ---
Clone Of: Environment:
Last Closed: 2008-07-22 12:50:00 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description masanari iida 2008-06-27 07:21:57 UTC 
Description of problem:
test with valgrind, dmesg(8) seemed to forget to free a block.

Version-Release number of selected component (if applicable):
util-linux-2.13-0.47.el5

How reproducible:
always

Steps to Reproduce:
1. install valgrind-3.2.3-2 from Fedora.
2. valgrind --tool=memcheck --leak-check=full dmesg

  
Actual results:

==16082==
==16082== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 12 from 1)
==16082== malloc/free: in use at exit: 131,080 bytes in 1 blocks.
==16082== malloc/free: 31 allocs, 30 frees, 133,063 bytes allocated.
==16082== For counts of detected errors, rerun with: -v
==16082== searching for pointers to 1 not-freed blocks.
==16082== checked 46,568 bytes.
==16082==
==16082== 131,080 bytes in 1 blocks are definitely lost in loss record 1 of 1
==16082==    at 0x40054E5: malloc (vg_replace_malloc.c:149)
==16082==    by 0x804887B: (within /bin/dmesg)
==16082==    by 0x35ADEB: (below main) (in /lib/libc-2.5.so)
==16082==
==16082== LEAK SUMMARY:
==16082==    definitely lost: 131,080 bytes in 1 blocks.   <==
==16082==      possibly lost: 0 bytes in 0 blocks.
==16082==    still reachable: 0 bytes in 0 blocks.
==16082==         suppressed: 0 bytes in 0 blocks.


Expected results:
No memory leak

Additional info:

[root@localhost ~]# rpm -qf /bin/dmesg
util-linux-2.13-0.47.el5
Comment 1 masanari iida 2008-06-27 09:13:00 UTC 
Track down the leak with self compile version of dmesg(8),
valgrind pointed out line 121 in dmesg.c.

==19700== 131,080 bytes in 1 blocks are definitely lost in loss record 1 of 1
==19700==    at 0x40054E5: malloc (vg_replace_malloc.c:149)
==19700==    by 0x80487FB: main (dmesg.c:121)
==19700==

    119         if (bufsize) {
    120                 sz = bufsize + 8;
    121                 buf = (char *) malloc(sz);
    122                 n = klogctl(cmd, buf, sz);
    123         } else {
    124                 sz = 16392;
    125                 while (1) {
    126                         buf = (char *) malloc(sz);
    127                         n = klogctl(3, buf, sz);        /* read only */
    128                         if (n != sz || sz > (1<<28))
    129                                 break;
    130                         free(buf);
    131                         sz *= 4;
    132                 }
Comment 2 Karel Zak 2008-07-22 12:50:00 UTC 
On Linux all memory is freed after process exit and many utils relies on this
feature. I don't think this as a fatal problem which should be fixed in RHEL update.

I'll close this report. Please, reopen, if you believe that the problem is
important and should be fixed.