[PATCH v2 2/3] rseq: remove redundant access_ok()

From: Eric Dumazet
Date: Tue Apr 13 2021 - 12:23:58 EST


From: Eric Dumazet <edumazet@xxxxxxxxxx>

After commit 8f2817701492 ("rseq: Use get_user/put_user rather
than __get_user/__put_user") we no longer need
an access_ok() call from __rseq_handle_notify_resume()

Mathieu pointed out the same cleanup can be done
in rseq_syscall().

Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Cc: Boqun Feng <boqun.feng@xxxxxxxxx>
Cc: Arjun Roy <arjunroy@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/rseq.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/kernel/rseq.c b/kernel/rseq.c
index f020f18f512a3f6241c3c9b104ce50e4d2c6188c..cfe01ab5253c1c424c0e8b25acbb6a8e1b41a5b6 100644
--- a/kernel/rseq.c
+++ b/kernel/rseq.c
@@ -273,8 +273,6 @@ void __rseq_handle_notify_resume(struct ksignal *ksig, struct pt_regs *regs)

if (unlikely(t->flags & PF_EXITING))
return;
- if (unlikely(!access_ok(t->rseq, sizeof(*t->rseq))))
- goto error;
ret = rseq_ip_fixup(regs);
if (unlikely(ret < 0))
goto error;
@@ -301,8 +299,7 @@ void rseq_syscall(struct pt_regs *regs)

if (!t->rseq)
return;
- if (!access_ok(t->rseq, sizeof(*t->rseq)) ||
- rseq_get_rseq_cs(t, &rseq_cs) || in_rseq_cs(ip, &rseq_cs))
+ if (rseq_get_rseq_cs(t, &rseq_cs) || in_rseq_cs(ip, &rseq_cs))
force_sig(SIGSEGV);
}

--
2.31.1.295.g9ea45b61b8-goog