[glibc] malloc: Use __getrandom_nocancel during tcache initiailization

[glibc] malloc: Use __getrandom_nocancel during tcache initiailization

[Florian Weimer]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=7187efd0aa270c83c428ea6cd0e1cffc34b41a74

commit 7187efd0aa270c83c428ea6cd0e1cffc34b41a74
Author: Florian Weimer <fweimer@redhat.com>
Date:   Mon Aug 1 15:49:07 2022 +0200

    malloc: Use __getrandom_nocancel during tcache initiailization
    
    Cancellation currently cannot happen at this point because dlopen
    as used by the unwind link always performs additional allocations
    for libgcc_s.so.1, even if it has been loaded already as a dependency
    of the main executable.  But it seems prudent not to rely on this
    quirk.
    
    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

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

diff --git a/malloc/malloc.c b/malloc/malloc.c
index bd3c76ed31..430d204156 100644
--- a/malloc/malloc.c
+++ b/malloc/malloc.c
@@ -254,6 +254,7 @@
 /* For tcache double-free check.  */
 #include <random-bits.h>
 #include <sys/random.h>
+#include <not-cancel.h>
 
 /*
   Debugging:
@@ -3153,7 +3154,7 @@ static uintptr_t tcache_key;
 static void
 tcache_key_initialize (void)
 {
-  if (__getrandom (&tcache_key, sizeof(tcache_key), GRND_NONBLOCK)
+  if (__getrandom_nocancel (&tcache_key, sizeof(tcache_key), GRND_NONBLOCK)
       != sizeof (tcache_key))
     {
       tcache_key = random_bits ();