linux-kernel - [tip: sched/core] rseq: Remove redundant access

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Date:   Thu, 15 Apr 2021 08:37:34 -0000
From:   "tip-bot2 for Eric Dumazet" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Eric Dumazet <edumazet@...gle.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: sched/core] rseq: Remove redundant access_ok()

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     0ed96051531ecc6965f6456d25b19b9b6bdb5c28
Gitweb:        https://git.kernel.org/tip/0ed96051531ecc6965f6456d25b19b9b6bdb5c28
Author:        Eric Dumazet <edumazet@...gle.com>
AuthorDate:    Tue, 13 Apr 2021 13:33:51 -07:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Wed, 14 Apr 2021 18:04:09 +02:00

rseq: Remove redundant access_ok()

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@...gle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Link: https://lkml.kernel.org/r/20210413203352.71350-3-eric.dumazet@gmail.com
---
 kernel/rseq.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/kernel/rseq.c b/kernel/rseq.c
index f020f18..cfe01ab 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);
 }