From: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date: Wed, 24 Jun 2020 06:47:15 +0000 (+0100)
Subject: nptl: Don't madvise user provided stack
X-Git-Tag: glibc-2.32~171
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=087942251f26d5fd5802b8d14e47d460263a0c4d;p=thirdparty%2Fglibc.git

nptl: Don't madvise user provided stack

User provided stack should not be released nor madvised at
thread exit because it's owned by the user.

If the memory is shared or file based then MADV_DONTNEED
can have unwanted effects. With memory tagging on aarch64
linux the tags are dropped and thus it may invalidate
pointers.

Tested on aarch64-linux-gnu with MTE, it fixes

FAIL: nptl/tst-stack3
FAIL: nptl/tst-stack3-mem
---

diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index 35a9927cf25..6d6ab88960e 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -549,8 +549,9 @@ START_THREAD_DEFN
     }
 #endif
 
-  advise_stack_range (pd->stackblock, pd->stackblock_size, (uintptr_t) pd,
-		      pd->guardsize);
+  if (!pd->user_stack)
+    advise_stack_range (pd->stackblock, pd->stackblock_size, (uintptr_t) pd,
+			pd->guardsize);
 
   if (__glibc_unlikely (pd->cancelhandling & SETXID_BITMASK))
     {