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stdlib/tst-setcontext9 test suite failure (#1623519)

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This commit is contained in:
Florian Weimer 2018-09-26 22:04:43 +02:00
parent dc43d3ff16
commit b972da9df0
2 changed files with 105 additions and 1 deletions
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100
glibc-rh1623519.patch Normal file
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@ -0,0 +1,100 @@
commit a55e109709af55e6ed67d3f9536cac5d929c982e
Author: Carlos O'Donell <carlos@redhat.com>
Date: Wed Sep 5 01:16:42 2018 -0400
Fix tst-setcontext9 for optimized small stacks.
If the compiler reduces the stack usage in function f1 before calling
into function f2, then when we swapcontext back to f1 and continue
execution we may overwrite registers that were spilled to the stack
while f2 was executing. Later when we return to f2 the corrupt
registers will be reloaded from the stack and the test will crash. This
was most commonly observed on i686 with __x86.get_pc_thunk.dx and
needing to save and restore $edx. Overall i686 has few registers and
the spilling to the stack is bound to happen, therefore the solution to
making this test robust is to split function f1 into two parts f1a and
f1b, and allocate f1b it's own stack such that subsequent execution does
not overwrite the stack in use by function f2.
Tested on i686 and x86_64.
Signed-off-by: Carlos O'Donell <carlos@redhat.com>
(cherry picked from commit 791b350dc725545e3f9b5db0f97ebdbc60c9735f)
diff --git a/stdlib/tst-setcontext9.c b/stdlib/tst-setcontext9.c
index 4636ce9030fa38a7..db8355766ca7b906 100644
--- a/stdlib/tst-setcontext9.c
+++ b/stdlib/tst-setcontext9.c
@@ -41,26 +41,55 @@ f2 (void)
}
static void
-f1 (void)
+f1b (void)
{
- puts ("start f1");
- if (getcontext (&ctx[2]) != 0)
- {
- printf ("%s: getcontext: %m\n", __FUNCTION__);
- exit (EXIT_FAILURE);
- }
if (done)
{
- puts ("set context in f1");
+ puts ("set context in f1b");
if (setcontext (&ctx[3]) != 0)
{
printf ("%s: setcontext: %m\n", __FUNCTION__);
exit (EXIT_FAILURE);
}
}
+ exit (EXIT_FAILURE);
+}
+
+static void
+f1a (void)
+{
+ char st2[32768];
+ puts ("start f1a");
+ if (getcontext (&ctx[2]) != 0)
+ {
+ printf ("%s: getcontext: %m\n", __FUNCTION__);
+ exit (EXIT_FAILURE);
+ }
+ ctx[2].uc_stack.ss_sp = st2;
+ ctx[2].uc_stack.ss_size = sizeof st2;
+ ctx[2].uc_link = &ctx[0];
+ makecontext (&ctx[2], (void (*) (void)) f1b, 0);
f2 ();
}
+/* The execution path through the test looks like this:
+ do_test (call)
+ -> "making contexts"
+ -> "swap contexts"
+ f1a (via swapcontext to ctx[1], with alternate stack)
+ -> "start f1a"
+ f2 (call)
+ -> "swap contexts in f2"
+ f1b (via swapcontext to ctx[2], with alternate stack)
+ -> "set context in f1b"
+ do_test (via setcontext to ctx[3], main stack)
+ -> "setcontext"
+ f2 (via setcontext to ctx[4], with alternate stack)
+ -> "end f2"
+
+ We must use an alternate stack for f1b, because if we don't then the
+ result of executing an earlier caller may overwrite registers
+ spilled to the stack in f2. */
static int
do_test (void)
{
@@ -79,7 +108,7 @@ do_test (void)
ctx[1].uc_stack.ss_sp = st1;
ctx[1].uc_stack.ss_size = sizeof st1;
ctx[1].uc_link = &ctx[0];
- makecontext (&ctx[1], (void (*) (void)) f1, 0);
+ makecontext (&ctx[1], (void (*) (void)) f1a, 0);
puts ("swap contexts");
if (swapcontext (&ctx[3], &ctx[1]) != 0)
{

6
glibc.spec
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@ -1,6 +1,6 @@
%define glibcsrcdir glibc-2.28
%define glibcversion 2.28
%define glibcrelease 12%{?dist}
%define glibcrelease 13%{?dist}
# Pre-release tarballs are pulled in from git using a command that is
# effectively:
#
@ -169,6 +169,7 @@ Patch33: glibc-1622674-1.patch
Patch34: glibc-1622674-2.patch
Patch35: glibc-rh1631338-1.patch
Patch36: glibc-rh1631338-2.patch
Patch37: glibc-rh1623519.patch
##############################################################################
# Continued list of core "glibc" package information:
@ -1910,6 +1911,9 @@ fi
%files -f compat-libpthread-nonshared.filelist -n compat-libpthread-nonshared
%changelog
* Wed Sep 26 2018 Florian Weimer <fweimer@redhat.com> - 2.28-13
- stdlib/tst-setcontext9 test suite failure (#1623519)
* Wed Sep 26 2018 Florian Weimer <fweimer@redhat.com> - 2.28-12
- gethostid: Missing NULL check for gethostbyname_r result (#1631338)