[glibc] nptl: rseq failure after registration on main thread is fatal

[glibc] nptl: rseq failure after registration on main thread is fatal

[Florian Weimer]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a41c8e92350e744a4bc639df5025153d05263e7f

commit a41c8e92350e744a4bc639df5025153d05263e7f
Author: Florian Weimer <fweimer@redhat.com>
Date:   Thu Dec 9 09:49:32 2021 +0100

    nptl: rseq failure after registration on main thread is fatal
    
    This simplifies the application programming model.
    
    Browser sandboxes have already been fixed:
    
      Sandbox is incompatible with rseq registration
      <https://bugzilla.mozilla.org/show_bug.cgi?id=1651701>
    
      Allow rseq in the Linux sandboxes. r=gcp
      <https://hg.mozilla.org/mozilla-central/rev/042425712eb1>
    
      Sandbox needs to support rseq system call
      <https://bugs.chromium.org/p/chromium/issues/detail?id=1104160>
    
      Linux sandbox: Allow rseq(2)
      <https://chromium.googlesource.com/chromium/src.git/+/230675d9ac8f1>
    
    Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>

Diff:
---
 nptl/pthread_create.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index 4608fd9068..c097fc54e6 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -370,7 +370,8 @@ start_thread (void *arg)
   /* Register rseq TLS to the kernel.  */
   {
     bool do_rseq = THREAD_GETMEM (pd, flags) & ATTR_FLAG_DO_RSEQ;
-    rseq_register_current_thread (pd, do_rseq);
+    if (!rseq_register_current_thread (pd, do_rseq) && do_rseq)
+      __libc_fatal ("Fatal glibc error: rseq registration failed\n");
   }
 
 #ifndef __ASSUME_SET_ROBUST_LIST