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Bug 585696 - app-misc/screen-4.3.1-r1: segmentation fault on command if argument length >=21 (e.g. screen-256color-bce-s)
Summary: app-misc/screen-4.3.1-r1: segmentation fault on command if argument length >=...
Alias: None
Product: Gentoo Linux
Classification: Unclassified
Component: Current packages (show other bugs)
Hardware: All Linux
: Normal major (vote)
Assignee: Sven Wegener
Depends on: 586428
  Show dependency tree
Reported: 2016-06-12 13:29 UTC by Andrew Savchenko
Modified: 2016-06-26 09:55 UTC (History)
2 users (show)

See Also:
Package list:
Runtime testing required: ---

emerge --info (,11.14 KB, text/plain)
2016-06-12 13:29 UTC, Andrew Savchenko
screen-4.3.1-term-length.patch (screen-4.3.1-term-length.patch,393 bytes, patch)
2016-06-12 13:44 UTC, Andrew Savchenko
Details | Diff
screen-4.3.1-termlen.patch (screen-4.3.1-termlen.patch,5.79 KB, patch)
2016-06-12 14:34 UTC, Andrew Savchenko
Details | Diff

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Description Andrew Savchenko gentoo-dev 2016-06-12 13:29:58 UTC
Created attachment 437250 [details]
emerge --info


screen-4.3.1-r1 segfaults if term is set to a value longer than 20 chars, e.g.:

$ cat ~/.screenrc
term screen-256color-bce-s

Here is backtrace:

# gdb /usr/bin/screen core
Core was generated by `/usr/bin/SCREEN'.
Program terminated with signal SIGABRT, Aborted.
#0  0xa76e6bd1 in __kernel_vsyscall ()
(gdb) bt
#0  0xa76e6bd1 in __kernel_vsyscall ()
#1  0xa74860c9 in raise () from /lib/
#2  0xa74877e4 in abort () from /lib/
#3  0x0804df59 in CoreDump (sigsig=11) at screen.c:1717
#4  <signal handler called>
#5  0x0806d8c3 in MakeTermcap (aflag=0) at termcap.c:947
#6  0x0807f77f in DoAction (act=act@entry=0xafe469ac, key=key@entry=-1) at process.c:2684
#7  0x08084123 in DoCommand (argv=argv@entry=0xafe469ec, argl=argl@entry=0xafe46aec) at process.c:4662
#8  0x08059615 in RcLine (ubuf=ubuf@entry=0xafe46c1c "term", ubufl=ubufl@entry=2048) at fileio.c:385
#9  0x0805a548 in FinishRc (rcfilename=0x0) at fileio.c:330
#10 0x0804c885 in main (ac=<optimized out>, av=<optimized out>) at screen.c:1440

For debugging program was build using CFLAGS="-O2 -pipe -ggdb3".

Looks like the reason comes from termcap.c:75:
char screenterm[20];        /* new $TERM, usually "screen" */

I'll test a fix and will report back later.
Comment 1 Andrew Savchenko gentoo-dev 2016-06-12 13:34:45 UTC
And this is how screen is configured:

$ eix -e screen
     Installed versions:  4.3.1-r1{tbz2}(03:44:08 PM 06/12/2016)(pam -debug -multiuser -nethack -selinux)
Comment 2 Andrew Savchenko gentoo-dev 2016-06-12 13:43:19 UTC
> Looks like the reason comes from termcap.c:75:
> char screenterm[20];        /* new $TERM, usually "screen" */

Indeed this is the cause. Patch below fixes segfault.
Comment 3 Andrew Savchenko gentoo-dev 2016-06-12 13:44:04 UTC
Created attachment 437252 [details, diff]
Comment 4 Andrew Savchenko gentoo-dev 2016-06-12 14:34:43 UTC
Created attachment 437260 [details, diff]

screenterm length is actually hardcoded in more places...

Upstream already fixed this issue in git:

However, upstream patch doesn't apply to 4.3.1, because many code changes were made. So I backported commit mentioned above to 4.3.1.

Seems to work fine here.
Comment 5 Andrew Savchenko gentoo-dev 2016-06-19 21:22:51 UTC
This issue was kindly fixed by upstream in the new screen-4.4.0 release.
Comment 6 Jeroen Roovers gentoo-dev 2016-06-26 09:51:01 UTC
Fixed in 4.4.0.