Prevent underflow in memcached_*_response_decrement macros
#124
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@@ Coverage Diff @@
## v1.x #124 +/- ##
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- Coverage 68% 68% -0%
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Files 194 194
Lines 17479 17479
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- Hits 11930 11915 -15
- Misses 5549 5564 +15
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Hello, we ran into a case where
instance->cursor_active_underflows here:libmemcached/src/libmemcached/response.cc
Line 748 in bcc1a6e
leading to a near-infinite loop here:
libmemcached/src/libmemcached/get.cc
Lines 190 to 192 in bcc1a6e
It seems to occur once every couple hours on a staging host under Apache 2.4 and PHP 7.3 against memcached 1.6.6. We weren't able to pinpoint the exact conditions to reproduce, nor the source of the bug. Maybe a missing
memcached_*_response_incrementor memory corruption?This appears to be a regression from 1.0.18 which we were running previously.
The patch mitigates but doesn't fix the bug.