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linux/arch/x86/entry
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Andy Lutomirski 7657a398c1 x86/entry/compat: Keep TS_COMPAT set during signal delivery 
commit 4e79e182b4 upstream.

Signal delivery needs to know the sign of an interrupted syscall's
return value in order to detect -ERESTART variants.  Normally this
works independently of bitness because syscalls internally return
long.  Under ptrace, however, this can break, and syscall_get_error
is supposed to sign-extend regs->ax if needed.

We were clearing TS_COMPAT too early, though, and this prevented
sign extension, which subtly broke syscall restart under ptrace.

Reported-by: Robert O'Callahan <robert@ocallahan.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: c5c46f59e4 ("x86/entry: Add new, comprehensible entry and exit handlers written in C")
Link: http://lkml.kernel.org/r/cbce3cf545522f64eb37f5478cb59746230db3b5.1455142412.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2016-04-12 09:08:32 -07:00
..
syscalls mm: mlock: add new mlock system call 2015-11-05 19:34:48 -08:00
vdso x86/entry: Restore traditional SYSENTER calling convention 2015-12-21 16:05:01 +01:00
vsyscall x86/entry/vsyscall: Fix undefined symbol warning 2015-09-21 09:56:59 +02:00
calling.h x86/asm/entry/64: Save all regs on interrupt entry 2015-07-07 10:59:07 +02:00
common.c x86/entry/compat: Keep TS_COMPAT set during signal delivery 2016-04-12 09:08:32 -07:00
entry_32.S x86/entry: Restore traditional SYSENTER calling convention 2015-12-21 16:05:01 +01:00
entry_64.S x86/entry/64: Fix irqflag tracing wrt context tracking 2015-11-24 09:55:02 +01:00
entry_64_compat.S x86/entry/compat: Add missing CLAC to entry_INT80_32 2016-03-03 15:07:30 -08:00
Makefile x86/entry: Move C entry and exit code to arch/x86/entry/common.c 2015-07-07 10:59:05 +02:00
syscall_32.c x86/syscalls: Give sys_call_ptr_t a useful type 2015-10-09 09:41:08 +02:00
syscall_64.c x86/syscalls: Give sys_call_ptr_t a useful type 2015-10-09 09:41:08 +02:00
thunk_32.S Merge branch 'x86-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-06-22 17:59:09 -07:00
thunk_64.S Merge branch 'x86-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-06-22 17:59:09 -07:00