src/patches/bash/bash51-012

   1                              BASH PATCH REPORT
   2                              =================
   3
   4 Bash-Release:   5.1
   5 Patch-ID:       bash51-012
   6
   7 Bug-Reported-by:        Nikolay Borisov <nborisov@suse.com>
   8 Bug-Reference-ID:       <1a715205-06ce-413b-c1c0-2f5639ce06c0@suse.com>
   9 Bug-Reference-URL:      https://lists.gnu.org/archive/html/bug-bash/2020-11/msg00091.html
  10
  11 Bug-Description:
  12
  13 There is a possible race condition that arises when a child process receives
  14 a signal trapped by the parent before it can reset the signal dispositions.
  15 The child process is not supposed to trap the signal in this circumstance.
  16
  17 Patch (apply with `patch -p0'):
  18
  19 *** ../bash-20201118/command.h  2020-08-14 15:04:39.000000000 -0400
  20 --- command.h   2020-11-27 15:18:02.000000000 -0500
  21 ***************
  22 *** 125,128 ****
  23 --- 125,129 ----
  24   #define SUBSHELL_COPROC       0x40    /* subshell from a coproc pipeline */
  25   #define SUBSHELL_RESETTRAP 0x80       /* subshell needs to reset trap strings on first call to trap */
  26 + #define SUBSHELL_IGNTRAP 0x100  /* subshell should reset trapped signals from trap_handler */
  27
  28   /* A structure which represents a word. */
  29
  30 *** ../bash-20201118/execute_cmd.c      2020-11-23 14:16:48.000000000 -0500
  31 --- execute_cmd.c       2020-11-27 16:43:25.000000000 -0500
  32 ***************
  33 *** 1548,1551 ****
  34 --- 1548,1554 ----
  35     reset_signal_handlers ();
  36     subshell_environment |= SUBSHELL_RESETTRAP;
  37 +   /* Note that signal handlers have been reset, so we should no longer
  38 +     reset the handler and resend trapped signals to ourselves. */
  39 +   subshell_environment &= ~SUBSHELL_IGNTRAP;
  40
  41     /* We are in a subshell, so forget that we are running a trap handler or
  42 ***************
  43 *** 4321,4325 ****
  44           cmdflags |= CMD_NO_FORK;
  45
  46 !         subshell_environment = SUBSHELL_FORK;         /* XXX */
  47           if (pipe_in != NO_PIPE || pipe_out != NO_PIPE)
  48             subshell_environment |= SUBSHELL_PIPE;
  49 --- 4324,4329 ----
  50           cmdflags |= CMD_NO_FORK;
  51
  52 !         /* We redo some of what make_child() does with SUBSHELL_IGNTRAP */
  53 !         subshell_environment = SUBSHELL_FORK|SUBSHELL_IGNTRAP;        /* XXX */
  54           if (pipe_in != NO_PIPE || pipe_out != NO_PIPE)
  55             subshell_environment |= SUBSHELL_PIPE;
  56 ***************
  57 *** 4575,4578 ****
  58 --- 4580,4584 ----
  59           reset_signal_handlers ();
  60           subshell_environment |= SUBSHELL_RESETTRAP;
  61 +         subshell_environment &= ~SUBSHELL_IGNTRAP;
  62
  63           if (async)
  64 ***************
  65 *** 5515,5518 ****
  66 --- 5521,5525 ----
  67         /* Cancel traps, in trap.c. */
  68         restore_original_signals ();
  69 +       subshell_environment &= ~SUBSHELL_IGNTRAP;
  70
  71   #if defined (JOB_CONTROL)
  72
  73 *** ../bash-20201118/jobs.c     2020-08-04 10:17:39.000000000 -0400
  74 --- jobs.c      2020-11-27 16:39:56.000000000 -0500
  75 ***************
  76 *** 2218,2221 ****
  77 --- 2218,2223 ----
  78         pid_t mypid;
  79
  80 +       subshell_environment |= SUBSHELL_IGNTRAP;
  81 +
  82         /* If this ends up being changed to modify or use `command' in the
  83          child process, go back and change callers who free `command' in
  84 diff -rC 2 ../bash-20201118/nojobs.c nojobs.c
  85 *** ../bash-20201118/nojobs.c   2020-07-08 10:11:25.000000000 -0400
  86 --- nojobs.c    2020-11-27 16:38:36.000000000 -0500
  87 ***************
  88 *** 576,579 ****
  89 --- 576,581 ----
  90   #endif
  91
  92 +       subshell_environment |= SUBSHELL_IGNTRAP;
  93 +
  94         default_tty_job_signals ();
  95       }
  96
  97 *** ../bash-20201118/sig.c      2020-11-23 13:22:17.000000000 -0500
  98 --- sig.c       2020-11-28 10:21:43.000000000 -0500
  99 ***************
 100 *** 56,60 ****
 101   #endif
 102
 103 ! extern void initialize_siglist ();
 104
 105   #if !defined (JOB_CONTROL)
 106 --- 56,61 ----
 107   #endif
 108
 109 ! extern void initialize_siglist PARAMS((void));
 110 ! extern void set_original_signal PARAMS((int, SigHandler *));
 111
 112   #if !defined (JOB_CONTROL)
 113 ***************
 114 *** 256,259 ****
 115 --- 257,267 ----
 116         XHANDLER(i) = oact.sa_handler;
 117         XSAFLAGS(i) = oact.sa_flags;
 118 +
 119 + #if 0
 120 +       set_original_signal (XSIG(i), XHANDLER(i));     /* optimization */
 121 + #else
 122 +       set_original_signal (XSIG(i), act.sa_handler);  /* optimization */
 123 + #endif
 124 +
 125         /* Don't do anything with signals that are ignored at shell entry
 126          if the shell is not interactive. */
 127
 128 *** ../bash-20201118/subst.c    2020-11-16 10:33:15.000000000 -0500
 129 --- subst.c     2020-11-27 16:07:00.000000000 -0500
 130 ***************
 131 *** 5952,5955 ****
 132 --- 5952,5956 ----
 133         /* Cancel traps, in trap.c. */
 134         restore_original_signals ();    /* XXX - what about special builtins? bash-4.2 */
 135 +       subshell_environment &= ~SUBSHELL_IGNTRAP;
 136         QUIT;   /* catch any interrupts we got post-fork */
 137         setup_async_signals ();
 138 ***************
 139 *** 6383,6386 ****
 140 --- 6384,6388 ----
 141         QUIT;   /* catch any interrupts we got post-fork */
 142         subshell_environment |= SUBSHELL_RESETTRAP;
 143 +       subshell_environment &= ~SUBSHELL_IGNTRAP;
 144       }
 145
 146
 147 diff -rC 2 ../bash-20201118/trap.c trap.c
 148 *** ../bash-20201118/trap.c     2020-11-28 12:04:07.000000000 -0500
 149 --- trap.c      2020-11-28 10:22:10.000000000 -0500
 150 ***************
 151 *** 482,485 ****
 152 --- 482,511 ----
 153       }
 154
 155 +   /* This means we're in a subshell, but have not yet reset the handler for
 156 +      trapped signals. We're not supposed to execute the trap in this situation;
 157 +      we should restore the original signal and resend the signal to ourselves
 158 +      to preserve the Posix "signal traps that are not being ignored shall be
 159 +      set to the default action" semantics. */
 160 +   if ((subshell_environment & SUBSHELL_IGNTRAP) && trap_list[sig] != (char *)IGNORE_SIG)
 161 +     {
 162 +       sigset_t mask;
 163 +
 164 +       /* Paranoia */
 165 +       if (original_signals[sig] == IMPOSSIBLE_TRAP_HANDLER)
 166 +       original_signals[sig] = SIG_DFL;
 167 +
 168 +       restore_signal (sig);
 169 +
 170 +       /* Make sure we let the signal we just caught through */
 171 +       sigemptyset (&mask);
 172 +       sigprocmask (SIG_SETMASK, (sigset_t *)NULL, &mask);
 173 +       sigdelset (&mask, sig);
 174 +       sigprocmask (SIG_SETMASK, &mask, (sigset_t *)NULL);
 175 +
 176 +       kill (getpid (), sig);
 177 +
 178 +       SIGRETURN (0);
 179 +     }
 180 +
 181     if ((sig >= NSIG) ||
 182         (trap_list[sig] == (char *)DEFAULT_SIG) ||
 183
 184 *** ../bash-5.1/patchlevel.h    2020-06-22 14:51:03.000000000 -0400
 185 --- patchlevel.h        2020-10-01 11:01:28.000000000 -0400
 186 ***************
 187 *** 26,30 ****
 188      looks for to find the patch level (for the sccs version string). */
 189
 190 ! #define PATCHLEVEL 11
 191
 192   #endif /* _PATCHLEVEL_H_ */
 193 --- 26,30 ----
 194      looks for to find the patch level (for the sccs version string). */
 195
 196 ! #define PATCHLEVEL 12
 197
 198   #endif /* _PATCHLEVEL_H_ */