[CONC-497] Memory Leak found with LSan in ma_net.c Created: 2020-09-11  Updated: 2022-01-11  Resolved: 2021-03-02

Status: Closed
Project: MariaDB Connector/C
Component/s: None
Affects Version/s: 3.0.6, 3.1.10
Fix Version/s: N/A

Type: Bug Priority: Major
Reporter: Animesh Soni Assignee: Richard Stracke
Resolution: Incomplete Votes: 0
Labels: None
Environment:

Centos 7 docker image


 Description   

I filed a ticket for this: https://jira.mariadb.org/browse/CONC-495
but they closed it without answering my question.

Can someone please answer my question regarding how the leak was fixed? And what triggers the leak? 

Georg Richter added a comment - 2 days ago
 
fixed - rev. 64a421295322214c827441cf824091dc874ddc6a
 
 
 
 
 
Animesh Soni added a comment - Yesterday - edited
 
I just checked that the ma_net.c looks is the same for 3.0.6 and 3.1.10. Would you be able to provide context on what was triggering the leak and how was it fixed?
 
Or provide me a link to another JIRA issue if there was one for the leak ?

Issue:

Hey our LSan run identified a memory leak in ma_net.c file. The memory allocated on line 311 is not freed when the function returns on line 340.

You should add this code before returning "ma_net_real_write" on line 340:

#ifdef HAVE_COMPRESS
 
  if (net->compress)
 
    free((char*) packet);
 
#endif

This is what the LSan callstack looks like:

Direct leak of 102 byte(s) in 6 object(s) allocated from:

0 0x7f92a113ab78 in malloc /home/fcm/Perforce/SDK/UnixClang/dev/scripts/llvm_RELEASE_401_source/projects/compiler-rt/lib/asan/asan_malloc_linux.cc:66
 
1 0x7f92a0383b55 in ma_net_real_write /mariadb-connector-c-3.0.6-src/libmariadb/ma_net.c:311
 
2 0x7f92a0383c57 in ma_net_flush /mariadb-connector-c-3.0.6-src/libmariadb/ma_net.c:166
 
3 0x7f92a0383fd8 in ma_net_write_command /mariadb-connector-c-3.0.6-src/libmariadb/ma_net.c:244
 
4 0x7f92a038b8ba in mthd_my_send_cmd /mariadb-connector-c-3.0.6-src/libmariadb/mariadb_lib.c:395
 
5 0x7f92a0392736 in net_stmt_close /mariadb-connector-c-3.0.6-src/libmariadb/mariadb_stmt.c:1324
 
6 0x7f92a0393333 in mysql_stmt_close /mariadb-connector-c-3.0.6-src/libmariadb/mariadb_stmt.c:1344
 
7 0x7f92a03aa9c7 in mysql_stmt_close_start_internal /mariadb-connector-c-3.0.6-src/libmariadb/mariadb_async.c:1509
 
8 0x7f92a03aeda0 in my_context_spawn /mariadb-connector-c-3.0.6-src/libmariadb/ma_context.c:201

Can I get a better context on how we could be running into this issue? Are there any known workarounds?
(we are avoiding making a custom version of the package)

 Comments   
Comment by Georg Richter [ 2020-11-11 ]

What is wrong with previous fix for CONC-495 ? See https://github.com/mariadb-corporation/mariadb-connector-c/blame/v3.1.10/libmariadb/ma_net.c#L343

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