On 3/6/12 7:59 AM, Siddhesh Poyarekar wrote:
> Bash Version: 4.2
> Patch Level: 20
> Release Status: release
>
> Description:
>
> When a SIGCHLD is received in job control mode and a handler for the
> signal is installed, bash calls the trap handler within the signal
> handler itself. This is unsafe because the trap handler function
> run_sigchld_trap() uses the glibc malloc functions quite extensively
> (within the function itself and also the function it calls, i.e.
> parse_and_execute() ). This results in a deadlock and sometimes even a
> segmentation fault due to memory corruption.
>
> Repeat-By:
>
> $ cat > foo.sh
> #!/bin/sh
>
> check_stop_child_trap() {
> echo "child died!"
> }
>
> do_something() {
> while true; do
> true &
> done
> }
>
> trap check_stop_child_trap SIGCHLD
> do_something &
> do_something
>
> ^d
>
> $ bash
> $ . foo.sh
>
> ------------------
>
> The above may either hang or result in a segmentation fault.
>
> Fix:
>
> The attached patch fixes this by deferring execution of the trap
> handler by adding it to pending_sigs.
Good catch. Thanks for the report. The fix will be in the next release
of bash.
Chet
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU c...@case.edu http://cnswww.cns.cwru.edu/~chet/
