Configuration Information [Automatically generated, do not change]: Machine: x86_64 OS: linux-gnu Compiler: gcc Compilation CFLAGS: -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64' -DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-redhat-linux-gnu' -DCONF_VENDOR='redhat' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL -DHAVE_CONFIG_H -I. -I. -I./include -I./lib -D_GNU_SOURCE -DRECYCLES_PIDS -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic uname output: Linux office 2.6.35.10-74.fc14.x86_64 #1 SMP Thu Dec 23 16:04:50 UTC 2010 x86_64 x86_64 x86_64 GNU/Linux Machine Type: x86_64-redhat-linux-gnu
Bash Version: 4.1 Patch Level: 7 Release Status: release Description: There is a report of bash being miscompiled for cygwin when using gcc 4.3.4 -O2, but succeeding when compiled with -O1: http://cygwin.com/ml/cygwin/2011-02/msg00230.html Compiling with -Wextra reveals the culprit: execute_cmd.c: In function ‘execute_function.clone.2’: execute_cmd.c:4007:23: warning: variable ‘bash_source_a’ might be clobbered by ‘longjmp’ or ‘vfork’ execute_cmd.c:4007:39: warning: variable ‘bash_lineno_a’ might be clobbered by ‘longjmp’ or ‘vfork’ execute_cmd.c: In function ‘execute_in_subshell’: execute_cmd.c:1296:12: warning: variable ‘tcom’ might be clobbered by ‘longjmp’ or ‘vfork’ POSIX is clear that the value of an automatic variable changed between setjmp() and the subsequent longjmp() is unspecified unless the variable is marked volatile, but bash is violating this constraint and modifying several variables that cannot reliably be restored. Depending on what code transformations the compiler makes, this can lead to crashes; in cygwin's case, it appears that mere execution of a trap return handler can cause bash to corrupt its own stack. Repeat-By: make rm execute_cmd.o make CFLAGS='-Wextra -O2' Fix: --- execute_cmd.c.orig 2011-02-09 11:53:13.470850670 -0700 +++ execute_cmd.c 2011-02-09 11:53:48.422939088 -0700 @@ -1293,7 +1293,7 @@ int user_subshell, return_code, function_value, should_redir_stdin, invert; int ois, user_coproc; int result; - COMMAND *tcom; + COMMAND *volatile tcom; USE_VAR(user_subshell); USE_VAR(user_coproc); @@ -4004,7 +4004,7 @@ char *debug_trap, *error_trap, *return_trap; #if defined (ARRAY_VARS) SHELL_VAR *funcname_v, *nfv, *bash_source_v, *bash_lineno_v; - ARRAY *funcname_a, *bash_source_a, *bash_lineno_a; + ARRAY *funcname_a, *volatile bash_source_a, *volatile bash_lineno_a; #endif FUNCTION_DEF *shell_fn; char *sfile, *t; -- Eric Blake ebl...@redhat.com +1-801-349-2682 Libvirt virtualization library http://libvirt.org
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