From: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date: Wed, 14 Oct 2015 15:58:41 +0000 (+0100)
Subject: [BZ #19129][ARM] Fix _dl_tlsdesc_resolve_hold to save r0
X-Git-Tag: glibc-2.23~347
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1fae5a6800b07d0a8225664ac65a628bbe98cae7;p=thirdparty%2Fglibc.git

[BZ #19129][ARM] Fix _dl_tlsdesc_resolve_hold to save r0

_dl_tlsdesc_resolve_hold calls into a C function that clobbers r0,
but it assumes the original argument is still in r0 after the call.
This can cause crash in case of concurrent TLS access when TLSDESC
is in use (-mtls-dialect=gnu2).

Run into this while fixing BZ 18572.

Both r0 and r1 are saved/restored so the stack remains 8 byte aligned.

	[BZ #19129]
	* sysdeps/arm/dl-tlsdesc.S (_dl_tlsdesc_resolve_hold): Save and restore
	r0 and r1.
---

diff --git a/ChangeLog b/ChangeLog
index 5b825cd3f4f..8a308891ea3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2015-10-14  Szabolcs Nagy  <szabolcs.nagy@arm.com>
+
+	[BZ #19129]
+	* sysdeps/arm/dl-tlsdesc.S (_dl_tlsdesc_resolve_hold): Save and restore
+	r0 and r1.
+
 2015-10-14  Namhyung Kim  <namhyung@gmail.com>
 
 	* manaual/argp.texi (Specifying Argp Parsers): Fix typo.
diff --git a/NEWS b/NEWS
index ed468ce7a6c..fd33e079f6f 100644
--- a/NEWS
+++ b/NEWS
@@ -20,7 +20,7 @@ Version 2.23
   18966, 18967, 18969, 18970, 18977, 18980, 18981, 18985, 19003, 19007,
   19012, 19016, 19018, 19032, 19046, 19049, 19050, 19059, 19071, 19074,
   19076, 19077, 19078, 19079, 19085, 19086, 19088, 19094, 19095, 19124,
-  19125
+  19125, 19129
 
 * The obsolete header <regexp.h> has been removed.  Programs that require
   this header must be updated to use <regex.h> instead.
diff --git a/sysdeps/arm/dl-tlsdesc.S b/sysdeps/arm/dl-tlsdesc.S
index e42ca68eda2..33a269573ec 100644
--- a/sysdeps/arm/dl-tlsdesc.S
+++ b/sysdeps/arm/dl-tlsdesc.S
@@ -196,21 +196,30 @@ _dl_tlsdesc_lazy_resolver:
 	eabi_fnstart
 	.align 2
 _dl_tlsdesc_resolve_hold:
-	eabi_save ({r2,r3,ip,lr})
-	push	{r2, r3, ip, lr}
-	cfi_adjust_cfa_offset (16)
-	cfi_rel_offset (r2, 0)
-	cfi_rel_offset (r3, 4)
-	cfi_rel_offset (ip, 8)
-	cfi_rel_offset (lr, 12)
+	/* r0 is saved so its original value can be used after the call and
+	   r1 is saved only to keep the stack aligned.  (r0 points to the tls
+	   descriptor, it is passed to _dl_tlsdesc_resolve_hold_fixup which
+	   is a void function that may clobber r0, later r0 is used to load
+	   the new resolver.)  */
+	eabi_save ({r0,r1,r2,r3,ip,lr})
+	push	{r0, r1, r2, r3, ip, lr}
+	cfi_adjust_cfa_offset (24)
+	cfi_rel_offset (r0, 0)
+	cfi_rel_offset (r1, 4)
+	cfi_rel_offset (r2, 8)
+	cfi_rel_offset (r3, 12)
+	cfi_rel_offset (ip, 16)
+	cfi_rel_offset (lr, 20)
 	adr	r1, _dl_tlsdesc_resolve_hold
 	bl	_dl_tlsdesc_resolve_hold_fixup
-	pop	{r2, r3, ip, lr}
-	cfi_adjust_cfa_offset (-16)
+	pop	{r0, r1, r2, r3, ip, lr}
+	cfi_adjust_cfa_offset (-24)
 	cfi_restore (lr)
 	cfi_restore (ip)
 	cfi_restore (r3)
 	cfi_restore (r2)
+	cfi_restore (r1)
+	cfi_restore (r0)
 	sfi_breg r0, \
 	ldr     r1, [\B, #4]
 	BX      (r1)