In short the easy handle needs to be disconnected from its connection at
this point since the connection still is serving other easy handles.
In our app we can reliably reproduce a crash in our http2 stress test
that is fixed by this change. I can't easily reproduce the same test in
a small example.
This is the gdb/asan output:
==11785==ERROR: AddressSanitizer: heap-use-after-free on address 0xe9f4fb80 at pc 0x09f41f19 bp 0xf27be688 sp 0xf27be67c
READ of size 4 at 0xe9f4fb80 thread T13 (RESOURCE_HTTP)
#0 0x9f41f18 in curl_multi_remove_handle /path/to/source/3rdparty/curl/lib/multi.c:666
0xe9f4fb80 is located 0 bytes inside of 1128-byte region [0xe9f4fb80,0xe9f4ffe8)
freed by thread T13 (RESOURCE_HTTP) here:
#0 0xf7b1b5c2 in __interceptor_free /opt/toolchain/src/gcc-6.2.0/libsanitizer/asan/asan_malloc_linux.cc:45
#1 0x9f7862d in conn_free /path/to/source/3rdparty/curl/lib/url.c:2808
#2 0x9f78c6a in Curl_disconnect /path/to/source/3rdparty/curl/lib/url.c:2876
#3 0x9f41b09 in multi_done /path/to/source/3rdparty/curl/lib/multi.c:615
#4 0x9f48017 in multi_runsingle /path/to/source/3rdparty/curl/lib/multi.c:1896
#5 0x9f490f1 in curl_multi_perform /path/to/source/3rdparty/curl/lib/multi.c:2123
#6 0x9c4443c in perform /path/to/source/src/net/resourcemanager/ResourceManagerCurlThread.cpp:854
#7 0x9c445e0 in ...
#8 0x9c4cf1d in ...
#9 0xa2be6b5 in ...
#10 0xf7aa5780 in asan_thread_start /opt/toolchain/src/gcc-6.2.0/libsanitizer/asan/asan_interceptors.cc:226
#11 0xf4d3a16d in __clone (/lib/i386-linux-gnu/libc.so.6+0xe716d)
previously allocated by thread T13 (RESOURCE_HTTP) here:
#0 0xf7b1ba27 in __interceptor_calloc /opt/toolchain/src/gcc-6.2.0/libsanitizer/asan/asan_malloc_linux.cc:70
#1 0x9f7dfa6 in allocate_conn /path/to/source/3rdparty/curl/lib/url.c:3904
#2 0x9f88ca0 in create_conn /path/to/source/3rdparty/curl/lib/url.c:5797
#3 0x9f8c928 in Curl_connect /path/to/source/3rdparty/curl/lib/url.c:6438
#4 0x9f45a8c in multi_runsingle /path/to/source/3rdparty/curl/lib/multi.c:1411
#5 0x9f490f1 in curl_multi_perform /path/to/source/3rdparty/curl/lib/multi.c:2123
#6 0x9c4443c in perform /path/to/source/src/net/resourcemanager/ResourceManagerCurlThread.cpp:854
#7 0x9c445e0 in ...
#8 0x9c4cf1d in ...
#9 0xa2be6b5 in ...
#10 0xf7aa5780 in asan_thread_start /opt/toolchain/src/gcc-6.2.0/libsanitizer/asan/asan_interceptors.cc:226
#11 0xf4d3a16d in __clone (/lib/i386-linux-gnu/libc.so.6+0xe716d)
SUMMARY: AddressSanitizer: heap-use-after-free /path/to/source/3rdparty/curl/lib/multi.c:666 in curl_multi_remove_handle
Shadow bytes around the buggy address:
0x3d3e9f20: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x3d3e9f30: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x3d3e9f40: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x3d3e9f50: fd fd fd fd fd fd fd fd fd fd fd fd fd fa fa fa
0x3d3e9f60: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x3d3e9f70:[fd]fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x3d3e9f80: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x3d3e9f90: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x3d3e9fa0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x3d3e9fb0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
0x3d3e9fc0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Heap right redzone: fb
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack partial redzone: f4
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
==11785==ABORTING
Thread 14 "RESOURCE_HTTP" received signal SIGABRT, Aborted.
[Switching to Thread 0xf27bfb40 (LWP 12324)]
0xf7fd8be9 in __kernel_vsyscall ()
(gdb) bt
#0 0xf7fd8be9 in __kernel_vsyscall ()
#1 0xf4c7ee89 in __GI_raise (sig=6) at ../sysdeps/unix/sysv/linux/raise.c:54
#2 0xf4c803e7 in __GI_abort () at abort.c:89
#3 0xf7b2ef2e in __sanitizer::Abort () at /opt/toolchain/src/gcc-6.2.0/libsanitizer/sanitizer_common/sanitizer_posix_libcdep.cc:122
#4 0xf7b262fa in __sanitizer::Die () at /opt/toolchain/src/gcc-6.2.0/libsanitizer/sanitizer_common/sanitizer_common.cc:145
#5 0xf7b21ab3 in __asan::ScopedInErrorReport::~ScopedInErrorReport (this=0xf27be171, __in_chrg=<optimized out>) at /opt/toolchain/src/gcc-6.2.0/libsanitizer/asan/asan_report.cc:689
#6 0xf7b214a5 in __asan::ReportGenericError (pc=166993689, bp=4068206216, sp=4068206204, addr=3925146496, is_write=false, access_size=4, exp=0, fatal=true) at /opt/toolchain/src/gcc-6.2.0/libsanitizer/asan/asan_report.cc:1074
#7 0xf7b21fce in __asan::__asan_report_load4 (addr=3925146496) at /opt/toolchain/src/gcc-6.2.0/libsanitizer/asan/asan_rtl.cc:129
#8 0x09f41f19 in curl_multi_remove_handle (multi=0xf3406080, data=0xde582400) at /path/to/source3rdparty/curl/lib/multi.c:666
#9 0x09f6b277 in Curl_close (data=0xde582400) at /path/to/source3rdparty/curl/lib/url.c:415
#10 0x09f3354e in curl_easy_cleanup (data=0xde582400) at /path/to/source3rdparty/curl/lib/easy.c:860
#11 0x09c6de3f in ...
#12 0x09c378c5 in ...
#13 0x09c48133 in ...
#14 0x09c4d092 in ...
#15 0x0a2be6b6 in ...
#16 0xf7aa5781 in asan_thread_start (arg=0xf2d22938) at /opt/toolchain/src/gcc-6.2.0/libsanitizer/asan/asan_interceptors.cc:226
#17 0xf5de52b5 in start_thread (arg=0xf27bfb40) at pthread_create.c:333
#18 0xf4d3a16e in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:114
Fixes#1083
406506ca92