Re: Bash crashes with trapped SIGCHLD and read -t.

[lina]

On Friday 25,January,2013 12:28 AM, Chet Ramey wrote:
> On 1/24/13 8:35 AM, konsolebox wrote:
>> Hi. Is there a way to prevent this segmentation fault in Bash? I'm not sure
>> where the fault happens but when there's a function that handles a trap and
>> when a signal is caught during a session of read with -t, Bash crashes. An
>> example code that makes this happen is this:
> 
> I ran this script through around 6000 cycles on RHEL 5 using bash-4.2.42,
> built with and without the bash malloc, and didn't see a crash.

It's about "luck". Well ... I also produce this problem.

> How about a stack traceback from one of the crashes you get?

*** glibc detected *** /bin/bash: double free or corruption (fasttop):
0x0000000001810d30 ***
======= Backtrace: =========
/lib64/libc.so.6[0x34e5275676]
/bin/bash(read_builtin+0x143d)[0x47170d]
/bin/bash[0x42d54e]
/bin/bash[0x42f4f2]
/bin/bash(execute_command_internal+0x943)[0x430113]
/bin/bash[0x433283]
/bin/bash(execute_command_internal+0x89d)[0x43006d]
/bin/bash(execute_command+0x4e)[0x430dbe]
/bin/bash[0x4316e7]
/bin/bash(execute_command_internal+0xa45)[0x430215]
/bin/bash(execute_command+0x4e)[0x430dbe]
/bin/bash(reader_loop+0xa6)[0x41d526]
/bin/bash(main+0xe5e)[0x41ccde]
/lib64/libc.so.6(__libc_start_main+0xfd)[0x34e521ec5d]
/bin/bash[0x41af19]
======= Memory map: ========
00400000-004d5000 r-xp 00000000 fd:00 131170
 /bin/bash
006d4000-006de000 rw-p 000d4000 fd:00 131170
 /bin/bash
006de000-006e3000 rw-p 00000000 00:00 0
008dd000-008e6000 rw-p 000dd000 fd:00 131170
 /bin/bash
01806000-01827000 rw-p 00000000 00:00 0
 [heap]
31b4600000-31b461d000 r-xp 00000000 fd:00 2883648
 /lib64/libtinfo.so.5.7
31b461d000-31b481d000 ---p 0001d000 fd:00 2883648
 /lib64/libtinfo.so.5.7
31b481d000-31b4821000 rw-p 0001d000 fd:00 2883648
 /lib64/libtinfo.so.5.7
34e4e00000-34e4e1e000 r-xp 00000000 fd:00 2883634
 /lib64/ld-2.12.so
34e501e000-34e501f000 r--p 0001e000 fd:00 2883634
 /lib64/ld-2.12.so
34e501f000-34e5020000 rw-p 0001f000 fd:00 2883634
 /lib64/ld-2.12.so
34e5020000-34e5021000 rw-p 00000000 00:00 0
34e5200000-34e5375000 r-xp 00000000 fd:00 2883959
 /lib64/libc-2.12.so
34e5375000-34e5575000 ---p 00175000 fd:00 2883959
 /lib64/libc-2.12.so
34e5575000-34e5579000 r--p 00175000 fd:00 2883959
 /lib64/libc-2.12.so
34e5579000-34e557a000 rw-p 00179000 fd:00 2883959
 /lib64/libc-2.12.so
34e557a000-34e557f000 rw-p 00000000 00:00 0
34e5600000-34e5602000 r-xp 00000000 fd:00 2884013
 /lib64/libdl-2.12.so
34e5602000-34e5802000 ---p 00002000 fd:00 2884013
 /lib64/libdl-2.12.so
34e5802000-34e5803000 r--p 00002000 fd:00 2884013
 /lib64/libdl-2.12.so
34e5803000-34e5804000 rw-p 00003000 fd:00 2884013
 /lib64/libdl-2.12.so
34e9200000-34e9216000 r-xp 00000000 fd:00 2884025
 /lib64/libgcc_s-4.4.4-20100726.so.1
34e9216000-34e9415000 ---p 00016000 fd:00 2884025
 /lib64/libgcc_s-4.4.4-20100726.so.1
34e9415000-34e9416000 rw-p 00015000 fd:00 2884025
 /lib64/libgcc_s-4.4.4-20100726.so.1
7f89a4b3e000-7f89a4b3f000 rw-p 00000000 00:00 0
7f89a4b3f000-7f89a4b46000 r--s 00000000 fd:00 1312117
 /usr/lib64/gconv/gconv-modules.cache
7f89a4b46000-7f89aa9d7000 r--p 00000000 fd:00 1055982
 /usr/lib/locale/locale-archive
7f89aa9d7000-7f89aa9dc000 rw-p 00000000 00:00 0
7fff6514a000-7fff65160000 rw-p 00000000 00:00 0
 [stack]
7fff651ff000-7fff65200000 r-xp 00000000 00:00 0
 [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0
 [vsyscall]
Aborted (core dumped)


> 
> Chet
>