[Bug 4550] Segfault in Busybox while installing Ubuntu 11.10

bugzilla at busybox.net bugzilla at busybox.net
Mon Jan 30 11:10:22 UTC 2012


https://bugs.busybox.net/show_bug.cgi?id=4550

Denys Vlasenko <vda.linux at googlemail.com> changed:

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--- Comment #19 from Denys Vlasenko <vda.linux at googlemail.com> 2012-01-30 11:10:21 UTC ---
Created attachment 4010
  --> https://bugs.busybox.net/attachment.cgi?id=4010
Debugging patch

I looked at the data but, unfortunately, my crude debug additions didn't help
to pin down the location of the crash.

It's great that you are able to build and use your own busybox - the matching
busybox_unstripped is available, and we can map addresses to functions.

Please find attached patch which adds a SIGSEGV handler to init. It will print
something like this on SEGV:

signal:11 address:0x123 ip:0x80dba39
./busybox[0x80db94a]
[0xb786240c]
/bin/busybox[0x80dba39]
/bin/busybox[0x804dcaa]
/bin/busybox[0x804dccd]
/bin/busybox[0x804df7d]
/bin/busybox[0x804e018]
/lib/libc.so.6(__libc_start_main+0xf3)[0xb76916b3]
/bin/busybox[0x804d66d]

and then sleep forever. ip:ADDR and the trace would be very useful to see!

Can you apply the patch to 1.19.3 and try to reproduce the crash? If yes, send
me the resulting messages and the busybox_unstripped binary (exactly that
binary which was used to obtain the messages!)

Note: if you aren't using glibc and therefore build fails, remove "include
<execinfo.h>" and "glibc extension" block in handle_sigsegv(). We won't have a
backtrace, but the ip:ADDR will still be printed, and we'll know the location
where it SEGVed.

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