wsh: fix a crash when a symbol can't be loaded #39
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In case a symbol can be loaded dlsym() returns NULL. This need to be
handled instead of blindly passing the 0 address do dladdr(), otherwise
that causes a crash:
$ ./bin/wsh
init
WARNING: No binary loaded in memory. Try loadbin(). For help type help("loadbin").
[SIGSEGV] Read 0x19 (address not mapped to object)
0x7f7edd231cb1 /lib/x86_64-linux-gnu/libc.so.6(+0x14fcb1)
0x42017f52 ./bin/wsh(scan_syms+0x152)
0x420183c8 ./bin/wsh(parse_link_map_dyn+0x58)
0x4201c371 ./bin/wsh(wsh_run+0x61)
0x4200ecba ./bin/wsh(main+0x3a)
0x7f7edd10520a /lib/x86_64-linux-gnu/libc.so.6(+0x2320a)
0x7f7edd1052bc /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x7c)
0x4200ed0a ./bin/wsh(_start+0x2a)
Segmentation fault (core dumped)
This is reproducible for instance when wsh has been built against glibc
<= 2.33, but executed on glibc >= 2.34. This is due to the merge of
libdl.so into libc.so, resulting in libdl.so only containing weak
symbols. wsh then crashes when trying to dlsym the
_ITM_deregisterTMCloneTable symbol.
Rebuilding wcc against glibc >= 2.34 workarounds the problem as the
resulting wsh binary is not linked against libdl.so anymore.
endrazine
approved these changes
Nov 6, 2022
|
Hi Aurel32, Thanks for your bug report and patch :) Best regards, j- |
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In case a symbol can be loaded dlsym() returns NULL. This need to be handled instead of blindly passing the 0 address do dladdr(), otherwise that causes a crash:
$ ./bin/wsh
init
WARNING: No binary loaded in memory. Try loadbin(). For help type help("loadbin").
[SIGSEGV] Read 0x19 (address not mapped to object)
0x7f7edd231cb1 /lib/x86_64-linux-gnu/libc.so.6(+0x14fcb1)
0x42017f52 ./bin/wsh(scan_syms+0x152)
0x420183c8 ./bin/wsh(parse_link_map_dyn+0x58)
0x4201c371 ./bin/wsh(wsh_run+0x61)
0x4200ecba ./bin/wsh(main+0x3a)
0x7f7edd10520a /lib/x86_64-linux-gnu/libc.so.6(+0x2320a)
0x7f7edd1052bc /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0x7c)
0x4200ed0a ./bin/wsh(_start+0x2a)
Segmentation fault (core dumped)
This is reproducible for instance when wsh has been built against glibc <= 2.33, but executed on glibc >= 2.34. This is due to the merge of libdl.so into libc.so, resulting in libdl.so only containing weak symbols. wsh then crashes when trying to dlsym the _ITM_deregisterTMCloneTable symbol.
Rebuilding wcc against glibc >= 2.34 workarounds the problem as the resulting wsh binary is not linked against libdl.so anymore.