6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
[ Upstream commit 5475c03fa25f31cfd5f8c7e552f8d10347bbaad9 ]
If tracer wanted to skip a syscall return value was always
overwritten with -ENOSYS. Fix this by checking against original
syscall number and only return -ENOSYS, if it is negative.
Fixes: b6318a903d06 ("MIPS/ptrace: Pick up ptrace/seccomp changed syscalls")
Reviewed-by: Philippe Mathieu-Daudé <redacted>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/mips/kernel/ptrace.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index fdcaad9fba1dc..39dc17f456d5b 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -1318,8 +1318,12 @@ long arch_ptrace(struct task_struct *child, long request,
*/
asmlinkage long syscall_trace_enter(struct pt_regs *regs)
{
+ long syscall;
+
user_exit();
+ syscall = current_thread_info()->syscall;
+
if (test_thread_flag(TIF_SYSCALL_TRACE)) {
if (ptrace_report_syscall_entry(regs))
return -1;@@ -1355,7 +1359,7 @@ asmlinkage long syscall_trace_enter(struct pt_regs *regs)
* Negative syscall numbers are mistaken for rejected syscalls, but
* won't have had the return value set appropriately, so we do so now.
*/
- if (current_thread_info()->syscall < 0)
+ if (syscall < 0)
syscall_set_return_value(current, regs, -ENOSYS, 0);
return current_thread_info()->syscall;
}
--
2.53.0