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HAProxy - Load balancer
61575769ac
When no tag matches a known pool, we can inspect around to help figure
what could have possibly overwritten memory. The contents are printed
one machine word per line in hex, then using printable characters, and
when they can be resolved to a pointer, either the pool's pointer name
or a resolvable symbol with offset. The goal here is to help recognize
what is easily identifiable in memory.
For example applying the following patch to stream_free():
- pool_free(pool_head_stream, s);
+ pool_free(pool_head_stream, (void*)s+1);
Causes the following dump to be emitted:
FATAL: pool inconsistency detected in thread 1: tag mismatch on free().
caller: 0x59e968 (stream_free+0x6d8/0xa0a)
item: 0x13df5c1
pool: 0x12782c0 ('stream', size 888, real 904, users 1)
Tag does not match (0x4f00000000012782). Tag does not match any other pool.
Contents around address 0x13df5c1+888=0x13df939:
0x13df918 [00 00 00 00 00 00 00 00] [........]
0x13df920 [00 00 00 00 00 00 00 00] [........]
0x13df928 [00 00 00 00 00 00 00 00] [........]
0x13df930 [00 00 00 00 00 00 00 00] [........]
0x13df938 [c0 82 27 01 00 00 00 00] [..'.....] [pool:stream]
0x13df940 [4f c0 59 00 00 00 00 00] [O.Y.....] [stream_new+0x4f/0xbec]
0x13df948 [49 46 49 43 41 54 45 2d] [IFICATE-]
0x13df950 [81 02 00 00 00 00 00 00] [........]
0x13df958 [df 13 00 00 00 00 00 00] [........]
Other possible callers:
(...)
We notice that the tag references pool_head_stream with the allocation
point in stream_new. Another benefit is that a caller may be figured
from the tag even if the "caller" feature is not enabled, because upon
a free() we always put the caller's location into the tag. This should
be sufficient to debug most cases that normally require gdb.
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| .github | ||
| addons | ||
| admin | ||
| dev | ||
| doc | ||
| examples | ||
| include | ||
| reg-tests | ||
| scripts | ||
| src | ||
| tests | ||
| .cirrus.yml | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .travis.yml | ||
| BRANCHES | ||
| BSDmakefile | ||
| CHANGELOG | ||
| CONTRIBUTING | ||
| INSTALL | ||
| LICENSE | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
| SUBVERS | ||
| VERDATE | ||
| VERSION | ||
The HAProxy documentation has been split into a number of different files for ease of use. Please refer to the following files depending on what you're looking for : - INSTALL for instructions on how to build and install HAProxy - BRANCHES to understand the project's life cycle and what version to use - LICENSE for the project's license - CONTRIBUTING for the process to follow to submit contributions The more detailed documentation is located into the doc/ directory : - doc/intro.txt for a quick introduction on HAProxy - doc/configuration.txt for the configuration's reference manual - doc/lua.txt for the Lua's reference manual - doc/SPOE.txt for how to use the SPOE engine - doc/network-namespaces.txt for how to use network namespaces under Linux - doc/management.txt for the management guide - doc/regression-testing.txt for how to use the regression testing suite - doc/peers.txt for the peers protocol reference - doc/coding-style.txt for how to adopt HAProxy's coding style - doc/internals for developer-specific documentation (not all up to date)