From 5dfafca33cf5db5ca88af43f4f764c29a69aff18 Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Wed, 20 Dec 2023 19:42:12 -0800 Subject: x86-64: Fix the tcb field load for x32 [BZ #31185] _dl_tlsdesc_undefweak and _dl_tlsdesc_dynamic access the thread pointer via the tcb field in TCB: _dl_tlsdesc_undefweak: _CET_ENDBR movq 8(%rax), %rax subq %fs:0, %rax ret _dl_tlsdesc_dynamic: ... subq %fs:0, %rax movq -8(%rsp), %rdi ret Since the tcb field in TCB is a pointer, %fs:0 is a 32-bit location, not 64-bit. It should use "sub %fs:0, %RAX_LP" instead. Since _dl_tlsdesc_undefweak returns ptrdiff_t and _dl_make_tlsdesc_dynamic returns void *, RAX_LP is appropriate here for x32 and x86-64. This fixes BZ #31185. (cherry picked from commit 81be2a61dafc168327c1639e97b6dae128c7ccf3) --- NEWS | 1 + sysdeps/x86_64/dl-tlsdesc.S | 4 ++-- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/NEWS b/NEWS index 377660ece0..8ac1be6cb9 100644 --- a/NEWS +++ b/NEWS @@ -88,6 +88,7 @@ The following bugs are resolved with this release: -D_FILE_OFFSET_BITS=64 [30842] Stack read overflow in getaddrinfo in no-aaaa mode (CVE-2023-4527) [31184] FAIL: elf/tst-tlsgap + [31185] Incorrect thread point access in _dl_tlsdesc_undefweak and _dl_tlsdesc_dynamic Version 2.36 diff --git a/sysdeps/x86_64/dl-tlsdesc.S b/sysdeps/x86_64/dl-tlsdesc.S index 706856e095..7619e743e1 100644 --- a/sysdeps/x86_64/dl-tlsdesc.S +++ b/sysdeps/x86_64/dl-tlsdesc.S @@ -61,7 +61,7 @@ _dl_tlsdesc_return: _dl_tlsdesc_undefweak: _CET_ENDBR movq 8(%rax), %rax - subq %fs:0, %rax + sub %fs:0, %RAX_LP ret cfi_endproc .size _dl_tlsdesc_undefweak, .-_dl_tlsdesc_undefweak @@ -116,7 +116,7 @@ _dl_tlsdesc_dynamic: addq TLSDESC_MODOFF(%rdi), %rax .Lret: movq -16(%rsp), %rsi - subq %fs:0, %rax + sub %fs:0, %RAX_LP movq -8(%rsp), %rdi ret .Lslow: -- cgit 1.4.1