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x86-64: Fix the tcb field load for x32 [BZ #31185]

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_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 81be2a61da)
This commit is contained in:
H.J. Lu 2023-12-20 19:42:12 -08:00
parent 2d87262c1c
commit 5d1fe26b49
2 changed files with 3 additions and 2 deletions
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1
NEWS
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@ -85,6 +85,7 @@ The following bugs are resolved with this release:
[30804] F_GETLK, F_SETLK, and F_SETLKW value change for powerpc64 with
-D_FILE_OFFSET_BITS=64
[31184] FAIL: elf/tst-tlsgap
[31185] Incorrect thread point access in _dl_tlsdesc_undefweak and _dl_tlsdesc_dynamic
Security related changes:

4
sysdeps/x86_64/dl-tlsdesc.S
View File

@ -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: