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segfault bug in menu selection + diagnosis
- X-seq: zsh-workers 18128
- From: <jp-www@xxxxxxxxxxxxx>
- To: <zsh-workers@xxxxxxxxxx>
- Subject: segfault bug in menu selection + diagnosis
- Date: Sat, 18 Jan 2003 21:47:59 +0000 (GMT)
- Mailing-list: contact zsh-workers-help@xxxxxxxxxx; run by ezmlm
I'm new to zsh and have been playing with the nice completion stuff. I've
found a segfaulting bug which appears to be reproducable. This was against
zsh-4.0.6, but I've also confirmed it with the HEAD branch in CVS (18/1/03
Steps to reproduce:
1. Start a new shell which uses new-style completion and the following
zstyle ':completion:*:kill:*' menu yes select
zstyle ':completion:*:kill:*' force-list always
These aren't actually necessary -- if you press tab enough times to
get the menu select to appear it happens too.
2. Type 'kill '
3. Press tab to get menu selection of processes (so a single process ID
appears on the command line and the first process in the list is
4. Resize your terminal to make it a bit wider, causing a SIGWINCH
5. Press the UP arrow
6. Segmentation fault should occur
If it doesn't happen straight away, try starting afresh and moving around
a little bit with the arrows before resizing.
This was on an i386 RedHat 8.0 system. The info below pertains to
Backtrace indicates that the crash occurs in domenuselect() in
complist.c:2272, in a call to dosingle(**p), while deferencing p twice.
The memory it pointed to has been freed, and doing
print (char*) p
in gdb shows a string (in this case):
So I suppose the memory has been reused for some strings that
have been later allocated.
I don't know enough about the structure of the source code to fix the
problem, but I think it's happening because the zrefresh() that's
called as a result of handling the SIGWINCH (the signal is delivered
during the domenuselect call to getkeycmd() at line 1781) eventually
causes complistmatches() to be called, thus freeing the 'mtab' global
array unexpectedly (at least to domenuselect()), so 'p' is invalid.
Thanks. I hope I've provided enough information to resolve the issue.
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