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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38dcb781bdcsm6325791f8f.23.2025.02.09.02.56.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 09 Feb 2025 02:56:11 -0800 (PST) From: David Laight To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds Cc: David Laight , Alexander Viro , Christian Brauner , Jan Kara , Arnd Bergmann , Kees Cook Subject: [PATCH 2/2] fs: Use masked_user_read_access_begin() Date: Sun, 9 Feb 2025 10:56:00 +0000 Message-Id: <20250209105600.3388-3-david.laight.linux@gmail.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250209105600.3388-1-david.laight.linux@gmail.com> References: <20250209105600.3388-1-david.laight.linux@gmail.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Commit 2865baf54077a changed get_sigset_argpack() to use masked_user_access_begin() and avoid a slow synchronisation instruction. Replace the rather unwieldy code pattern with masked_user_read_access_begin(). Make the same change to get_compat_sigset_argpack(). Use masked_user_write_access_begin() in do_sys_poll() to avoid the size calculation and conditional branch for access_ok(). Code generated for get_sigset_argpack() is identical. Signed-off-by: David Laight --- fs/select.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/fs/select.c b/fs/select.c index 7da531b1cf6b..abe2c1a57274 100644 --- a/fs/select.c +++ b/fs/select.c @@ -776,9 +776,7 @@ static inline int get_sigset_argpack(struct sigset_argpack *to, { // the path is hot enough for overhead of copy_from_user() to matter if (from) { - if (can_do_masked_user_access()) - from = masked_user_access_begin(from); - else if (!user_read_access_begin(from, sizeof(*from))) + if (!masked_user_read_access_begin(&from, sizeof(*from))) return -EFAULT; unsafe_get_user(to->p, &from->p, Efault); unsafe_get_user(to->size, &from->size, Efault); @@ -1009,7 +1007,7 @@ static int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds, fdcount = do_poll(head, &table, end_time); poll_freewait(&table); - if (!user_write_access_begin(ufds, nfds * sizeof(*ufds))) + if (!masked_user_write_access_begin(&ufds, nfds * sizeof(*ufds))) goto out_fds; for (walk = head; walk; walk = walk->next) { @@ -1347,7 +1345,7 @@ static inline int get_compat_sigset_argpack(struct compat_sigset_argpack *to, struct compat_sigset_argpack __user *from) { if (from) { - if (!user_read_access_begin(from, sizeof(*from))) + if (!masked_user_read_access_begin(&from, sizeof(*from))) return -EFAULT; unsafe_get_user(to->p, &from->p, Efault); unsafe_get_user(to->size, &from->size, Efault);