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Commit 64f7b10a authored Mar 06, 2020 by Sven Schnelle Committed by Sasha Levin Jun 30, 2020

s390/ptrace: pass invalid syscall numbers to tracing



[ Upstream commit 00332c16b1604242a56289ff2b26e283dbad0812 ]

tracing expects to see invalid syscalls, so pass it through.
The syscall path in entry.S checks the syscall number before
looking up the handler, so it is still safe.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 453cfe18

arch/s390/kernel/entry.S

+1 −1

Original line number	Diff line number	Diff line
		@@ -368,9 +368,9 @@ ENTRY(system_call)
		jnz .Lsysc_nr_ok
		# svc 0: system call number in %r1
		llgfr %r1,%r1 # clear high word in r1
		sth %r1,__PT_INT_CODE+2(%r11)
		cghi %r1,NR_syscalls
		jnl .Lsysc_nr_ok
		sth %r1,__PT_INT_CODE+2(%r11)
		slag %r8,%r1,3
		.Lsysc_nr_ok:
		xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)

arch/s390/kernel/ptrace.c

+2 −4

Original line number	Diff line number	Diff line
		@@ -844,11 +844,9 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
		* call number to gprs[2].
		*/
		if (test_thread_flag(TIF_SYSCALL_TRACE) &&
		(tracehook_report_syscall_entry(regs) \|\|
		regs->gprs[2] >= NR_syscalls)) {
		tracehook_report_syscall_entry(regs)) {
		/*
		* Tracing decided this syscall should not happen or the
		* debugger stored an invalid system call number. Skip
		* Tracing decided this syscall should not happen. Skip
		* the system call and the system call restart handling.
		*/
		clear_pt_regs_flag(regs, PIF_SYSCALL);