Commit 42309ab4 authored by Will Deacon's avatar Will Deacon Committed by Russell King
Browse files

ARM: 8087/1: ptrace: reload syscall number after secure_computing() check

On the syscall tracing path, we call out to secure_computing() to allow
seccomp to check the syscall number being attempted. As part of this, a
SIGTRAP may be sent to the tracer and the syscall could be re-written by
a subsequent SET_SYSCALL ptrace request. Unfortunately, this new syscall
is ignored by the current code unless TIF_SYSCALL_TRACE is also set on
the current thread.

This patch slightly reworks the enter path of the syscall tracing code
so that we always reload the syscall number from
current_thread_info()->syscall after the potential ptrace traps.

Acked-by: default avatarKees Cook <>
Tested-by: default avatarKees Cook <>
Signed-off-by: default avatarWill Deacon <>
Signed-off-by: default avatarRussell King <>
parent 6980c3e2
......@@ -908,7 +908,7 @@ enum ptrace_syscall_dir {
static int tracehook_report_syscall(struct pt_regs *regs,
static void tracehook_report_syscall(struct pt_regs *regs,
enum ptrace_syscall_dir dir)
unsigned long ip;
......@@ -926,7 +926,6 @@ static int tracehook_report_syscall(struct pt_regs *regs,
current_thread_info()->syscall = -1;
regs->ARM_ip = ip;
return current_thread_info()->syscall;
asmlinkage int syscall_trace_enter(struct pt_regs *regs, int scno)
......@@ -938,7 +937,9 @@ asmlinkage int syscall_trace_enter(struct pt_regs *regs, int scno)
return -1;
if (test_thread_flag(TIF_SYSCALL_TRACE))
scno = tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);
tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);
scno = current_thread_info()->syscall;
if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
trace_sys_enter(regs, scno);
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