Kees Cook 085fe43238 ARM: ptrace: Restore syscall skipping for tracers ... [ Upstream commit 4697b5848b ] Since commit 4e57a4ddf6 ("ARM: 9107/1: syscall: always store thread_info->abi_syscall"), the seccomp selftests "syscall_errno" and "syscall_faked" have been broken. Both seccomp and PTRACE depend on using the special value of "-1" for skipping syscalls. This value wasn't working because it was getting masked by __NR_SYSCALL_MASK in both PTRACE_SET_SYSCALL and get_syscall_nr(). Explicitly test for -1 in PTRACE_SET_SYSCALL and get_syscall_nr(), leaving it exposed when present, allowing tracers to skip syscalls again. Cc: Russell King <linux@armlinux.org.uk> Cc: Arnd Bergmann <arnd@kernel.org> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: linux-arm-kernel@lists.infradead.org Fixes: 4e57a4ddf6 ("ARM: 9107/1: syscall: always store thread_info->abi_syscall") Reviewed-by: Arnd Bergmann <arnd@arndb.de> Link: https://lore.kernel.org/r/20230810195422.2304827-2-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Sasha Levin <sashal@kernel.org>		2023-09-13 09:42:28 +02:00
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asm	ARM: ptrace: Restore syscall skipping for tracers	2023-09-13 09:42:28 +02:00
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