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List:       kde-commits
Subject:    valgrind/coregrind
From:       Jeremy Fitzhardinge <jeremy () goop ! org>
Date:       2005-03-18 7:39:28
Message-ID: 20050318073928.4669616DE8 () office ! kde ! org
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CVS commit by fitzhardinge: 

sigsuspend was not sanitizing the temporary signal mask, which allowed
SIGVGKILL to be blocked.  This could cause process-exit to hang
indefinitely while threads ignore their requests to exit.

This patch sanitizes a copy of the temp sig mask, and points the syscall
to the sanitized version.


  M +21 -3     vg_syscalls.c   1.261


--- valgrind/coregrind/vg_syscalls.c  #1.260:1.261
@@ -5501,5 +5501,6 @@ PRE(sys_pause, MayBlock)
 PRE(sys_sigsuspend, MayBlock)
 {
-   /* The C library interface to sigsuspend just takes a pointer to
+   /* 
+      The C library interface to sigsuspend just takes a pointer to
       a signal mask but this system call has three arguments - the first
       two don't appear to be used by the kernel and are always passed as
@@ -5509,4 +5510,10 @@ PRE(sys_sigsuspend, MayBlock)
       In fact glibc normally uses rt_sigsuspend if it is available as
       that takes a pointer to the signal mask so supports more signals.
+
+      NOTE: (non-RT) sigsuspend can't block RT signals like
+      VKI_SIGVGKILL, so we don't need to worry about sanitizing its
+      mask, like we do with rt_sigsuspend.  We still need
+      tst->tmp_sig_mask to be set, since this is the effective signal
+      mask for any signal handlers which run during this syscall.
     */
    PRINT("sys_sigsuspend ( %d, %d, %d )", arg1,arg2,arg3 );
@@ -5520,5 +5527,6 @@ PRE(sys_sigsuspend, MayBlock)
 PRE(sys_rt_sigsuspend, MayBlock)
 {
-   /* The C library interface to sigsuspend just takes a pointer to
+   /* 
+      The C library interface to sigsuspend just takes a pointer to
       a signal mask but this system call has two arguments - a pointer
       to the mask and the number of bytes used by it. The kernel insists
@@ -5527,8 +5535,18 @@ PRE(sys_rt_sigsuspend, MayBlock)
     */
    PRINT("sys_rt_sigsuspend ( %p, %d )", arg1,arg2 );
-   PRE_REG_READ2(int, "rt_sigsuspend", vki_sigset_t *, mask, vki_size_t, size);
+   PRE_REG_READ2(int, "rt_sigsuspend", 
+                 vki_sigset_t *, mask, vki_size_t, size);
    if (arg1 != (Addr)NULL) {
       SYS_PRE_MEM_READ( "rt_sigsuspend(mask)", arg1, sizeof(vki_sigset_t) );
+
+      /* We need to make sure that the rt_sigsuspend doesn't mask more
+         signals than it is allowed, so we make a copy of the
+         temporary mask, sanitize that, and point the syscall to use
+         the copy.  (We need this copy anyway, because its the
+         effective signal mask during any signal handlers which are
+         called during this syscall.) */
       tst->tmp_sig_mask = *(vki_sigset_t *)arg1;
+      VG_(sanitize_client_sigmask)(tid, &tst->tmp_sig_mask);
+      arg1 = (Addr)&tst->tmp_sig_mask;
    }
 }


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