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[173.230.104.22]) by smtp.gmail.com with ESMTPSA id c21sm15183977iob.22.2018.12.25.14.47.45 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 25 Dec 2018 14:47:46 -0800 (PST) From: Kangjie Lu To: kjlu@umn.edu Cc: pakki001@umn.edu, Doug Gilbert , "James E.J. Bottomley" , "Martin K. Petersen" , Ingo Molnar , Peter Zijlstra , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] scsi: avoid a double-fetch and a redundant copy Date: Tue, 25 Dec 2018 16:47:18 -0600 Message-Id: <20181225224718.70271-1-kjlu@umn.edu> X-Mailer: git-send-email 2.17.2 (Apple Git-113) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org What we need is only "pack_id", so do not create a heap object or copy the whole object in. The fix efficiently copies "pack_id" only. Signed-off-by: Kangjie Lu --- drivers/scsi/sg.c | 4 ++-- kernel/sched/core.c | 18 ++++++++++++------ 2 files changed, 14 insertions(+), 8 deletions(-) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index 41774e4f9508..75842ceabc7f 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -446,8 +446,8 @@ sg_read(struct file *filp, char __user *buf, size_t count, loff_t * ppos) } if (old_hdr->reply_len < 0) { if (count >= SZ_SG_IO_HDR) { - retval = get_user(req_pack_id, - &((sg_io_hdr_t *)buf->pack_id)); + retval = + get_user(req_pack_id, &(sg_io_hdr_t __user *)buf->pack_id); if (retval) { retval = -EFAULT; goto free_old_hdr; diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 6fedf3a98581..0a55bdce9a42 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4447,7 +4447,7 @@ do_sched_setscheduler(pid_t pid, int policy, struct sched_param __user *param) */ static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *attr) { - u32 size; + u32 size, size_cp; int ret; if (!access_ok(VERIFY_WRITE, uattr, SCHED_ATTR_SIZE_VER0)) @@ -4460,15 +4460,17 @@ static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *a if (ret) return ret; + size_cp = size; + /* Bail out on silly large: */ if (size > PAGE_SIZE) goto err_size; /* ABI compatibility quirk: */ if (!size) - size = SCHED_ATTR_SIZE_VER0; + size_cp = SCHED_ATTR_SIZE_VER0; - if (size < SCHED_ATTR_SIZE_VER0) + else if (size < SCHED_ATTR_SIZE_VER0) goto err_size; /* @@ -4483,7 +4485,7 @@ static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *a unsigned char val; addr = (void __user *)uattr + sizeof(*attr); - end = (void __user *)uattr + size; + end = (void __user *)uattr + size_cp; for (; addr < end; addr++) { ret = get_user(val, addr); @@ -4492,13 +4494,17 @@ static int sched_copy_attr(struct sched_attr __user *uattr, struct sched_attr *a if (val) goto err_size; } - size = sizeof(*attr); + size_cp = sizeof(*attr); } - ret = copy_from_user(attr, uattr, size); + ret = copy_from_user(attr, uattr, size_cp); if (ret) return -EFAULT; + /* Sanity check if size was changed in user space */ + if (attr->size != size) + return -EINVAL; + /* * XXX: Do we want to be lenient like existing syscalls; or do we want * to be strict and return an error on out-of-bounds values? -- 2.17.2 (Apple Git-113)