Bug 238840 - 'top' segmentation fault on terminal resize
Summary: 'top' segmentation fault on terminal resize
Status: Closed FIXED
Alias: None
Product: Base System
Classification: Unclassified
Component: bin (show other bugs)
Version: 12.0-RELEASE
Hardware: Any Any
: --- Affects Only Me
Assignee: freebsd-bugs mailing list
Depends on:
Reported: 2019-06-27 05:36 UTC by igor-fbsdbugs
Modified: 2019-07-30 18:26 UTC (History)
2 users (show)

See Also:


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Description igor-fbsdbugs 2019-06-27 05:36:58 UTC
reproducible in any 12.0-RELEASE. (11.2-RELEASE and older do not seem to have the issue)

- run xterm or tmux, resize it to 75 or 76 or 77 columns (tried a few other sizes, seems to segfault only with these three)
- run top, let it update 1-2 times
- resize terminal wide (resizing narrow won't cause the segfault).

for completeness here is the backtrace (not too useful without debug symbols, but still)

# lldb -c top.core /usr/bin/top
(lldb) target create "/usr/bin/top" --core "top.core"
Core file '/root/top.core' (x86_64) was loaded.
(lldb) bt
* thread #1, name = 'top', stop reason = signal SIGSEGV
  * frame #0: 0x00000008004d87dd libc.so.7`memcpy + 205
    frame #1: 0x00000008004d65cd libc.so.7`___lldb_unnamed_symbol1635$$libc.so.7 + 397
    frame #2: 0x0000000800470a0c libc.so.7`___lldb_unnamed_symbol1024$$libc.so.7 + 14044
    frame #3: 0x00000008003ddd0f libc.so.7`vsnprintf + 287
    frame #4: 0x000000080031d81a libsbuf.so.6`sbuf_vprintf + 138
    frame #5: 0x000000080031db0d libsbuf.so.6`sbuf_printf + 141
    frame #6: 0x000000000020af47 top`___lldb_unnamed_symbol54$$top + 1319
    frame #7: 0x000000000020e428 top`___lldb_unnamed_symbol77$$top + 2296
    frame #8: 0x000000000020611b top`___lldb_unnamed_symbol1$$top + 283
Comment 1 Mark Johnston freebsd_committer 2019-07-07 17:54:21 UTC
FWIW, I'm not able to reproduce this on -CURRENT.
Comment 2 pprocacci 2019-07-30 15:16:33 UTC
I can confirm this bug on FBSD 12-RELEASE.

pprocacci@yoda:~ % lldb -c top.core /usr/lib/debug/usr/bin/top.debug
(lldb) target create "/usr/lib/debug/usr/bin/top.debug" --core "top.core"
Core file '/home/pprocacci/top.core' (x86_64) was loaded.
(lldb) bt
* thread #1, name = 'top', stop reason = signal SIGSEGV
  * frame #0: 0x00000000002085dd top.debug`u_process(line=0, newline=0x0000000000000000) at display.c:856
    frame #1: 0x000000000020e431 top.debug`main(argc=2147483647, argv=0x00000008007af000) at top.c:652
    frame #2: 0x000000000020611b top.debug`_start(ap=<unavailable>, cleanup=<unavailable>) at crt1.c:76

display.c:856 is the following:
    newline[screen_width] = '\0';
Comment 3 pprocacci 2019-07-30 16:10:14 UTC
(In reply to pprocacci from comment #2)

Following up with myself with a fix that maybe you'd like to employ:

# svnlite co https://svn.freebsd.org/base/head/usr.bin/top /usr/src/usr.bin/top.new
# cd /usr/src/usr.bin/top.new
# make
# make install

There has been memory allocation related work that does indeed fix this bug that's currently in current.
The above, will take that `top` from current and install it, fixing the bug you are encountering on 12-RELEASE.
Comment 4 Mark Johnston freebsd_committer 2019-07-30 16:59:00 UTC
(In reply to pprocacci from comment #3)
Can you verify that the problem is fixed on stable/12?  That is, if you fetch usr.bin/top from stable/12 instead of head, are you able to reproduce the crash?
Comment 5 pprocacci 2019-07-30 18:18:47 UTC
# svnlite co https://svn.freebsd.org/base/stable/12/usr.bin/top /usr/src/usr.bin/top.stable12
# cd /usr/src/usr.bin/top.stable12
# make
# make install

With the above, I can confirm that the bug _IS NOT_ present in stable 12.
Comment 6 Mark Johnston freebsd_committer 2019-07-30 18:26:14 UTC
(In reply to pprocacci from comment #5)
Thanks for confirming.  In that case I will resolve the bug as fixed in stable/12; the issue will be gone in 12.1.