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https://sourceware.org/git/glibc.git
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68448be208
This patch fixes the i386 sa_restorer field initialization for sigaction syscall for kernel with vDSO. As described in bug report, i386 Linux (and compat on x86_64) interprets SA_RESTORER clear with nonzero sa_restorer as a request for stack switching if the SS segment is 'funny'. This means that anything that tries to mix glibc's signal handling with segmentation (for instance through modify_ldt syscall) is randomly broken depending on what values lands in sa_restorer. The testcase added is based on Linux test tools/testing/selftests/x86/ldt_gdt.c, more specifically in do_multicpu_tests function. The main changes are: - C11 atomics instead of plain access. - Remove x86_64 support which simplifies the syscall handling and fallbacks. - Replicate only the test required to trigger the issue. Checked on i686-linux-gnu. [BZ #21269] * sysdeps/unix/sysv/linux/i386/Makefile (tests): Add tst-bz21269. * sysdeps/unix/sysv/linux/i386/sigaction.c (SET_SA_RESTORER): Clear sa_restorer for vDSO case. * sysdeps/unix/sysv/linux/i386/tst-bz21269.c: New file.
50 lines
990 B
Makefile
50 lines
990 B
Makefile
# The default ABI is 32.
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default-abi := 32
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ifeq ($(subdir),misc)
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sysdep_routines += ioperm iopl vm86
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tests += tst-bz21269
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$(objpfx)tst-bz21269: $(shared-thread-library)
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endif
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ifeq ($(subdir),elf)
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sysdep-dl-routines += libc-do-syscall
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sysdep-others += lddlibc4
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install-bin += lddlibc4
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endif
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ifeq ($(subdir),io)
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sysdep_routines += libc-do-syscall
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endif
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ifeq ($(subdir),nptl)
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libpthread-sysdep_routines += libc-do-syscall
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libpthread-shared-only-routines += libc-do-syscall
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endif
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ifeq ($(subdir),stdlib)
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gen-as-const-headers += ucontext_i.sym
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endif
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ifeq ($(subdir),csu)
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sysdep-dl-routines += sysdep
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ifeq (yes,$(build-shared))
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sysdep_routines += divdi3
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shared-only-routines += divdi3
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CPPFLAGS-divdi3.c = -Din_divdi3_c
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endif
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endif
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ifeq ($(subdir),nptl)
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# pull in __syscall_error routine
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libpthread-routines += sysdep
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libpthread-shared-only-routines += sysdep
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endif
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ifeq ($(subdir),rt)
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# pull in __syscall_error routine
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librt-routines += sysdep
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librt-shared-only-routines += sysdep
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endif
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