Re: [PATCH v2 2/2] ARM: ptrace: Restore syscall skipping for tracers
From: "Arnd Bergmann" <arnd@arndb.de>
Date: 2023-08-10 20:11:37
Also in:
linux-hardening, linux-mediatek, lkml
On Thu, Aug 10, 2023, at 21:54, Kees Cook wrote:
Since commit 4e57a4ddf6b0 ("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 <redacted>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: linux-arm-kernel@lists.infradead.org
Fixes: 4e57a4ddf6b0 ("ARM: 9107/1: syscall: always store
thread_info->abi_syscall")
Signed-off-by: Kees Cook <redacted>Reviewed-by: Arnd Bergmann <arnd@arndb.de> _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel